AN EVALUATION OF RIGHT-TURN-IN/RIGHT-TURN-OUT
RESTRICTIONS IN ACCESS MANAGEMENT
FINAL REPORT
SUBMITTED TO:
MICHIGAN DEPARTMENT OF TRANSPORTATION
SUBMITTED BY:
RICHARD W. LYLES, PHD, PE BILAL ZIA MALIK
AMNA CHAUDHRY GHASSAN ABU-LEBDEH, PHD, PE
M. ABRAR SIDDIQUI
DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING MICHIGAN STATE UNIVERSITY
30 SEPTEMBER 2009
ii
Technical Report Documentation Page 1. Report No.
RC-1539 2. Government Accession No.
3. MDOT Project Manager
Lauri Olsen
4. Title and Subtitle
An Evaluation of Right-Turn-In/Tight-Turn-Out Restrictions in
Access Management
5. Report Date
September 30, 2009 6. Performing Organization Code
7. Author(s)
Richard W. Lyles, PhD, PE, Bilal Z. Malik, Amna Chaudhry,
Ghassan Abu-Lebdeh, PhD, PE, M. Abrar Siddiqui
8. Performing Org. Report No.
9. Performing Organization Name and Address
Department of Civil and Environmental Engineering
Michigan State University
3546 Engineering Building
East Lansing, MI 48824-1226
10. Work Unit No. (TRAIS)
11. Contract No.
2006-0411/A9
11(a). Authorization No.
2006-0411/A9
12. Sponsoring Agency Name and Address
Michigan Department of Transportation
Real Estate Section
P.O. Box 30049
Lansing, MI 48909
13. Type of Report & Period Covered
Final Report, 2006-2009
14. Sponsoring Agency Code
15. Supplementary Notes
16. Abstract
Access management strategies are devised to facilitate travel mobility and improve safety. Direct
access especially left-turns in and out of developments can create significant problems for the traffic flow
and safety on the adjacent roadway and at the driveways. This study evaluates the safety and operational
impacts under various access configurations, and provides basic guidelines as to when left-turns at
driveways should be prohibited.
The safety considerations were found to be less significant compared to the operational concerns
since the crash reductions that might be expected from access restrictions appeared to be relatively
modest. The importance of review of crash history by site is emphasized.
Traffic simulation models were developed using VISSIM to analyze the operational impacts of
driveway turning restrictions at corner and mid-block sites. The results indicate that lesser the corner
clearance, more negative is the impact on driveway related delays. Also, the negative impact due to
mainline volume increment was more severe as compared to the increment in driveway volume. The
impact on the driveway operations was worse when the number of lanes on the adjacent roadway was less
than 5 or 4. The right-turn (in or out) driveway traffic was not critical from either the operations or safety
perspectives due to fewer conflict points. General guidelines are proposed for prohibition of left-turns in
and out for various combinations of mainline and driveway traffic volumes and corner clearances.
17. Key Words
Access Management
Right-Turn-In/Right-Turn-Out Restrictions
18. Distribution Statement
No restrictions. This document is available
to the public through the Michigan
Department of Transportation. 19. Security Classification - report
Unclassified 20. Security Classification - page
Unclassified 21. No. of Pages
67 (excluding
appendices)
22. Price
iii
Acknowledgement
This project was sponsored by the Michigan Department of Transportation (MDOT Contract # 2006-
0411/A9). The project manager for this work was Lauri Olsen and assistance and feedback provided by
her is acknowledged and greatly appreciated.
Disclaimer
The opinions, findings, conclusions and recommendations presented in this report are those of the
authors and do not necessarily reflect the official views and opinions of Michigan State University or the
Michigan Department of Transportation. This report does not constitute a standard, specification, or
regulation.
iv
Table of Contents
page Title Page i Technical Report Documentation Form ii Acknowledgement and Disclaimer iii Table of Contents iv Lists of (numbered) Figures and Tables vi Introduction 1 Review of Literature and Practice 2 Safety-Related Aspects of Turning Restrictions 6 Safety Effects of Prohibiting Direct Left-Turns 8 Safety Effects of Right-In/Right-Out Driveways within the Functional Area of the Intersection
9
Review of Practice 10 Analysis of Safety and Operational Impacts of Turn Restrictions in Michigan 16 Site Selection 16 Safety Impacts 17 Site 1: Walgreens, W. Saginaw Highway and Creyts Road, Lansing 18 Site 2: MSU Federal Credit Union, W. Saginaw Highway, Lansing 20 Site 3: Rite-Aid Pharmacy, M-36 (E Main Street) and Dexter Road, Pinckney 21 Site 4: Walgreens, Corunna Road (M-21) and Linden Road, Flint 23 Site 5: Krispy Kreme, M-21 (Corunna Road), Flint 25 Site 6: Tim Hortons, M-57 (Vienna Road), Clio 27 Site 7: BP Gas Station w/convenience market and fast-food restaurants, M-13, Lennon 28 Site 8: National City Bank and Advance Auto Parts, US-12 (Chicago Road) and Michigan Avenue, Coldwater
30
Site 9: Family Video, M-66 (Capital Avenue) and Emmett Street, Battle Creek 32 Discussion and Conclusions Operational Impacts 35 Basic Simulation Model and Assumptions 35 Operational Analysis Using VISSIM 37 Results for Model 1 (site 1) 37 Average Delay for Mainline Traffic 38 Average Delay for Driveway Traffic 39 50th Percentile Queue Length vs. Mainline Volume 42 Summary and Conclusions Based on Model 1 42 Recommended Access Control Guidelines Based on Model 1 Results 44 Results for Model 2 (sites 5 and 8) 45 Summary and Conclusions Based on Model 2 45 Evolving Guidelines Based on Model 2 47 Results for Model 3 (site 9) 49 Summary and Conclusions Based on Model 3 49 Evolving Guidelines Based on Model 3 49 Results for Model 4 (site 7) 50 Summary and Conclusions Based on Model 4 52 Evolving Guidelines Based on Model 4 52
v
Results for Model 5 (site 3) 54 Summary and Conclusions Based on Model 5 54 Evolving Guidelines Based on Model 5 55 Results for Model 6 (site 4) 57 Summary and Conclusions Based on Model 6 57 Evolving Guidelines Based on Model 6 58 Results for Model 7 (site 2) 58 Summary and Conclusions Based on Model 7 60 Evolving Guidelines Based on Model 7 62 Results for Model 8 (site 6) 62 Summary and Conclusions Based on Model 8 62 Evolving Guidelines Based on Model 8 62 Overarching Results and Recommendations 63 Summary of Results from Operational Modeling of Different Roadway Configurations 63 General Access Guidelines Based on Operational Modeling 63 Corner Sites 63 Mid-Block Sites 65 Overarching Safety Considerations 66 Discussion 66 References ref-1 Appendix 1: Summary of Turn-Restriction Practices Appendix 2: Description of Sites Appendix 3: Manual Data Collection Form Appendix 4: Crash Data Summary for All Sites Appendix 5: Additional Results for Model 1 Appendix 6: Results for Model 2 Appendix 7: Results for Model 3 Appendix 8: Results for Model 4 Appendix 9: Results for Model 5 Appendix 10: Results for Model 6 Appendix 11: Results for Model 7 Appendix 12: Results for Model 8
vi
Lists of (numbered) Figures and Tables page
Figures (numbered)
Figure 1. Percentages of driveway crashes by movement (NHI) 7
Figure 2. A right-turn movement followed by a U-turn (Huaguo et al. 2000) 8
Figure 3. Concept of directional median opening (FHWA 2004) 9
Figure 4. Restricting driveway to right-in/right-out in the functional area of intersection 10
Figure 5. Summary of Turn Restriction Policies 11
Figure 6. Summary of Guidelines for Driveway Types 12
Figure 7. Comparison of Average Total Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft and LT-in Vol=10vph
38
Figure 8. Comparison of Average Total Delay (sec/veh) vs. Mainline Volume (vph) CC=150ft, and LT-in Vol=50vph
39
Figure 9. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for C=150ft, and LT-in Vol=10vph
40
Figure 10. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
40
Figure 11. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
41
Figure 12. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
41
Figure 13. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=10vph
42
Figure 14. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=50vph
43
Figure 15. Summary of Left Turn Restriction Recommendations for Model 1 46
Figure 16. Summary of Left Turn Restriction Recommendations for Model 2 48
Figure 17. Summary of Left Turn Restriction Recommendations for Model 3 51
Figure 18. Summary of Left Turn Restriction Recommendations for Model 4 53
Figure 19. Summary of Left Turn Restriction Recommendations for Model 5 56
Figure 20. Summary of Left Turn Restriction Recommendations for Model 6 59
Figure 21. Summary of Left Turn Restriction Recommendations for Model 7 61
Figure 22. Summary of Left Turn Restriction Recommendations for Model 8 64
vii
Tables (numbered)
Table 1. Crash involvement percentages at commercial driveways (Box, 1998)
6
Table 2. Annual accident reductions per driveway for restricting both left-turn-in and out maneuvers (FHWA)
7
Table 3. Summary of crash analysis results for all study and similar sites 33
final report: page 1 of 67
AN EVALUATION OF RIGHT-TURN-IN/RIGHT-TURN-OUT RESTRICTIONS IN ACCESS MANAGEMENT
FINAL REPORT September 2009
INTRODUCTION
Access management strategies are devised to facilitate travel mobility and safety by controlling the
spacing, location, and design of driveways, medians and median openings. Direct access to
developments can create problems for the traffic flow and safety on the adjacent roadway and at the
driveways themselves. This study is an attempt to study specific access issues and to explore ways to
accommodate turning movements to and from developments while minimizing their negative impacts
on traffic operations. Left turns in and out of developments are generally the most problematic
movements in this context. One way to mitigate these impacts is to eliminate left turns, thus restricting
the access to the development to “right-turn-in/out only.” Turning restrictions are particularly
important when the access points are relatively close to existing intersections. The impacts of such
restrictions are found in several areas:
positive impacts for main-line traffic flow immediately in and around the entrances and exits to
the development where turning movements are significantly simplified, which should result in a
better level of service or at least less delay;
positive impacts from improved traffic safety which comes from elimination of several conflict
points at each entrance/exit and presumably lower crash frequencies;
negative impacts in terms of both traffic flow and safety which result from the increased
difficulty for any left-turning motorist who must go “around the block” to get to or from the
development;
negative impacts in terms of access to the development (e.g., some travelers may pass on by the
development rather than contend with restricted access).
In this context, the goals of the project are more narrowly focused:
review existing guidelines for restricting access;
assess the general magnitude of the safety impacts (e.g., number of crashes) and traveler delay
that result from restricting access based on a review of the literature and state practices;
final report: page 2 of 67
evaluate the safety-related outcomes of right-turn-only restrictions in several specific situations
where the technique has (or could have) been applied in Michigan;
assess the traffic flow related impacts (e.g., user delay) for a variety typical situations in Michigan
using traffic simulation models; and
develop general guidelines for when the techniques should be considered.
The results of the literature review are presented first. This is followed by a detailed review of existing
guidelines on access management strategies in various states; assessments of safety and traffic
operations-related impacts for specified sites in Michigan; and conclusions and recommendations. Note
that no attempt is made to assess or otherwise quantify the development-related economic impacts of
allowing or restricting access to adjacent land uses.
REVIEW OF LITERATURE AND PRACTICE
Left turns at driveways interfere with the operation of the adjacent roadway traffic, access to adjacent
properties, and cause safety problems and affect the level of service. Numerous studies have been
carried out to assess how the impacts of left turns can be best mitigated. The literature review was
conducted utilizing the TRIS-Online database of the Transportation Research Board (TRB), NCHRP
reports, the MDOT library, and the libraries at Michigan State University.
In a report prepared for the Ohio Department of Transportation (ODOT, 2003) by the University of
Dayton it was asserted that by changing driveway volumes from 50 to 200 vehicles per hour, there was
no significant impact on network delay. However, changes in the mainline volume, ranging from 500 to
1200 vehicles per hour per lane, increased the network delay significantly. The recommendation was
that mainline volume be used as a factor in determining the use of a direct left-turn alternative.
According to the study, for an existing site if there is a potential for several driveways to lead into one
development with sufficient traffic flow through the facility, left-turns could be restricted to all but one
intersection. This can be accomplished through the use of right-in/right-out islands and signs. Since the
latest ODOT Access Management Manual was issued in 2001, there is no readily available evidence that
these findings are incorporated by ODOT.
Some studies have shown that directional median openings are generally an effective method of
increasing vehicular safety and capacity. Sometimes in advance of downstream signalized intersection,
final report: page 3 of 67
mid-block directional median openings are provided to accommodate U-turns. However, there also have
been concerns expressed by general public regarding the safety of U-turns. In this context, a study was
carried out by Lu, Dissanayake, Xu and Williams (2001) in which they compared the safety performance
of two driveway left-turn treatments—direct left-turns and right-turns-only followed by U-turns (a
traveler exiting the development who want to turn left on the mainline is compelled to turn right and
then make a U-turn downstream). The research team examined crash history at 258 sites in Florida with
a total of 3,913 crashes over a three-year time period (1996 to 1998). The researchers found that the
overall crash rate for right-turns followed by U-turns was 17.8% less than that for direct left-turns. The
corresponding percentage reduction for property-damage-only crash rates was 6.4%, which was not
statistically significant. The injury/fatality crash rate for right-turns followed by U-turns was 27.3% less
than for direct left-turns. It should be noted, however, that providing U-turn opportunities is often not
realistic—most obviously when there is no median present.
Dorothy, Maleck and Nolf (1997) in their study carried out in Michigan concluded that boulevard designs
where indirect left turning strategies and signalized crossovers were typically superior to direct left-
turning strategies at signalized intersections. According to the study, the boulevard designs that used
direct left-turning strategies had proportionally higher amounts of delay than all other designs
considered, and their operation tended to fail as the percentage of traffic volume and left-turns
increased.
Chowdury, Derov, Tan, and Sadek (2005) performed a simulation analysis on prohibiting left-turn
movements at mid-block unsignalized driveways. They studied the impact of varying the arterial and
driveway volume on the effectiveness of restricting direct left-turns and providing alternative
movements. Three different alternatives were considered for left-turn treatments at mid-block
unsignalized intersections: no restriction of direct left-turns to or from the driveways; no direct left-
turns in or out of driveways and diverted traffic making a U-turn at the next intersections; and no direct
left-turns in or out of driveways and diverted traffic making a U-turn at mid-block. Two additional cases
were also evaluated: a jug-handle design; and no direct left-turns in or out of all but one driveway
(concentrated left-turn). The results showed very little operational difference between the no
restrictions on direct left-turns alternative versus the restrictions with the U-turn alternative movements
from site to site. According to the study, the jug-handle design appeared to be a superior alternative for
accommodating left-turn deterred traffic for multi-lane divided and undivided sites compared to mid-
final report: page 4 of 67
block or intersection U-turns. It was shown that the concentrated left-turn appeared to be an effective
solution for improving traffic flow conditions.
According to the NCHRP report 420: Impacts of Access Management Techniques (1999), travel times for
right-turns followed by U-turns are comparable with travel times for direct left-turns from driveways
under heavy volume conditions and when diversion distances are less than 0.5 miles. The report
authors also cite studies in Florida and Michigan where eliminating direct left turns from driveways
reduced crashes by about 20 percent.
Gluck, Haas, Mahmood, and Levinson (2000) conducted a study in which the impact of right-turning
vehicles on the through traffic was analyzed. Twenty-two (22) sites in Connecticut, Illinois, New Jersey,
and New York were studied. Each site represented an unsignalized driveway for a major traffic
generator along a suburban arterial roadway without deceleration lanes. The results of the analyses
were considered to be useful for establishing guidelines for deceleration lanes and spacing of
unsignalized driveways. The access spacing guidelines were suggested based on operational as well as
safety considerations. It was observed that for arterial right-lane volumes of 250 to 800 vehicles per
hour, the percentage of through vehicles impacted was about 0.18 times the right-turn volume. It was
suggested that this criterion can be used as a basis for providing right turn lanes.
In an Ohio-based study, Thieken and Croft (2004) evaluated the characteristics that impact violation
rates at right-in/right-out driveways. The research was focused exclusively on right-in/out driveways
with no center median on the highway to prohibit left-turns. Relevant characteristics related to
violations included the shape and size of the raised island, existence of vehicle storage on the arterial,
existence of delineators on the island, and the volume of traffic on the arterial.
A survey was developed by Chowdhury (2004) and sent to the 50 state transportation agencies to
inquire about their policies and procedures to assess the standard practice of restricting direct left-turns
from driveways, and to examine the use of alternatives to direct left-turns. Analysis of the results
revealed a lack of standards in most states. Only a few states had implemented a formal policy for
controlling left-turn treatments at driveways. Analysis of the survey results showed that midblock U-
turns and jug-handles have been successfully implemented.
final report: page 5 of 67
It is generally agreed that driveways should be placed sufficiently away from the main intersection to
avoid conflicts with the adjacent traffic flow and the intersection-related queues. AASHTO advises that
driveways not be permitted within the functional area of an intersection; therefore there should be
sufficient corner clearance to separate access connections from roadway intersections. The issue is also
addressed in the Access Management Manual (TRB, 2003) and it is advised to allow construction of an
access connection in case of no other alternatives along the property line, farthest from the
intersection. In such cases, agencies typically reserve the right to require directional connections (i.e.,
right-in/out, right-in-only, or right-out-only), or to require nonconforming corner properties to share
access with abutting properties.
A study on full versus directional median openings was conducted in Florida by Dissanayake and Lu
(2003). It was found that by converting a full median opening into a directional median opening, a
significant reduction occurred in weighted average delay experienced by left-turning vehicles whereas
total travel time remained unaffected. However, the safety effects of the conversion were highly
significant. The conflicts per hour were reduced by 49.9 percent and conflicts per thousand vehicles
were reduced by 46.3 percent.
In addition to corner clearance, driveways should be properly spaced to ensure safety. According to
Transportation Research Circular 456 (1996), spacing of driveways and streets needs to reflect sound
traffic engineering principles, driver behavior, and vehicle dynamics. Spacing should consider influences
such as highway function, access class and speed, volume of trucks, separation of conflict areas, the
number of conflict points, and locations of upstream and downstream driveways. The recommended
spacing values provided by this research circular range from 120-1875 ft, depending on the speed range
of 20-60 mph.
Other design standards like driveway width and corner clearance are also of concern. The Access
Management Manual (TRB, 2003) recommends driveway width ranging from 25-40 ft depending on
different design conditions. NCHRP Report 420: Impacts of Access Management Techniques (1999)
provides minimum corner clearance values required for certain speeds. These are summarized in the
spreadsheet in appendix 1.
final report: page 6 of 67
In concluding the literature review, it is found that there have been few or no studies specifically
regarding examination of turn restriction policies at driveways; however several studies have been
conducted to find alternatives for left-turn deterred traffic. Most researchers have found right-turn-only
followed by U-turns are better and safer option than direct left-turns. Furthermore, there are no
overarching national standards or guidelines for restriction to turning movements at driveways. The
development of uniform standards for Michigan to accommodate left-turn deterred traffic and for
driveway-related access management would be extremely beneficial for improvement of traffic flow and
safety at the driveways.
SAFETY-RELATED ASPECTS OF TURNING RESTRICTIONS
Left-turning movements to and from the driveways are usually considered to be the most problematic in
the context of driveway-related crashes. To understand the nature of driveway-related crashes,
Jonathan and Gattis (2008) performed a study on driveway collision patterns in a low-density urban
environment. A detailed examination of over 2,000 accident reports was performed to identify
driveway-related crashes. The findings of the study provided insight into which maneuver patterns and
situations are more problematic, and the relative risk for different user groups, both in terms of
frequency and severity. The research revealed that higher proportions of collisions were linked to left-
turn maneuvers and use of two-way left-turn lanes.
Several other research studies have also been conducted on the nature of accidents that occur at
driveways. In particular, Paul Box and Associates (1998) performed three studies on hundreds of
crashes at more than 1,300 driveways in three different communities in Illinois and found that left-
turning vehicles (exiting and entering) are involved in the majority of driveway-related crashes. The
description of crashes at commercial driveways by turning movement that was found in this study is
presented in table 1.
Table 1. Crash involvement percentages at commercial driveways (Box, 1998)
Turning movement Percent of total crashes at commercial driveways
Left-turning vehicles: Entering business driveways Exiting business driveways
43% to78% 14% to 31%
Right-turning vehicles: Entering business driveways Exiting business driveways
6% to 15% 2% to 15%
final report: page 7 of 67
According to the literature noted in the Access Management Location and Design Participant Notebook
(NHI year), 74% of driveway accidents involve left-turn maneuvers. Of these accidents, 47% are
associated with left turn-in maneuvers as shown in figure 1.
Figure 1. Percentages of driveway crashes by movement (NHI year)
According to the FHWA’s Technical Guidelines for the Control of Direct Access to Arterial Highway, a
typical right-in/right-out channelization warrant on undivided highways is that with speeds of 30-45
mph, ADT greater than 5,000 vpd, and driveway volumes of at least 1,000 vpd, it is required to prohibit
turns around 100vpd in number. Table 2 shows annual accident reductions per driveway for restricting
both left turn-in and -out maneuvers.
Table 2. Annual accident reductions per driveway for restricting both left-turn-in and out maneuvers (FHWA year)
Driveway Volume
(vpd)
Highway ADT (vpd)
Low
<5,000
Medium
5000-15,000
High
>15,000
Low<500 0.13 0.23 0.31
Medium 500-1,500 0.31 0.55 0.75
High>1,599 0.49 0.85 1.15
final report: page 8 of 67
Safety Effects of Prohibiting Direct Left-Turns
In order to address the operational and safety issues related with direct left turns, traffic engineers have
often looked at other alternatives of facilitating left turns one of which is right turns followed by U-
turns (indirect left turns). Castillo (2002) looked at the safety-related performance of direct left turns
from a driveway compared to right turns followed by U-turns. Results of a before-and-after study
conducted at a site where a direct left turn from a driveway was converted to a right turn followed by U-
turn showed significant and positive effects in terms of roadway crashes due to a lesser number of
conflicts. Figure 2 shows the movement of a right-turn followed by a U-turn.
Figure 2. A right-turn movement followed by a U-turn (Huaguo et al. 2000)
Other researchers have also found that the prohibiting left turns and providing alternative treatment
such as right turn followed by U-turn (through directional median opening) is effective in increasing
vehicular safety and capacity. Figure 3 shows the typical arrangement of directional median opening for
prohibiting direct outbound left-turns from driveway. Lu et al. (2001) carried out a safety study of two
driveway left-turn treatments: direct left-turns and right-turns followed by U-turns were compared.
The research team examined crash histories at 258 sites in Florida with a total of 3,913 crashes over a
three year time period (1996 to 1998). The findings were that the overall crash rate for right-turns
followed by U-turns was 17.8% less than that for direct left-turns. The corresponding reduction for
property-damage-only crash rates was 6.4%, which was not statistically significant. The injury/fatality
crash rate for right-turns followed by U-turns was 27.3% less than for direct left-turns.
final report: page 9 of 67
Figure 3. Concept of directional median opening (FHWA 2004)
Safety Effects of Right-In/Right-Out Driveways within the Functional Area of the Intersection
The performance of “right-in/right-out” restriction technique has been found to improve the safety at
adjacent roadway especially when the driveway is too close to or in the functional area of the
intersection. The functional area is that area near intersection that includes auxiliary lanes on roads.
Box (1998) presented the effects of intersections on driveway accidents. The research included a
detailed tabulation of over 15,000 accidents in two Illinois suburbs. The crashes were distributed on the
basis of type, location (intersection versus midblock conditions) and functional classification (major,
collector, and local). Neither of the cities placed any limitation on driveway proximity to intersections,
other than clearing the corner radius. Based on his findings, Box suggested that access management
policies regarding restricting driveways closer to intersections is a better and safer option than providing
the access point at a certain specified distance from the intersection. Figure 4 shows the concept of
right-in/right-out restriction in the functional area of intersection.
TRB’s Access Management Manual (TRB 2003) also addresses this issue and suggests only allowing a
driveway access point in cases where there are no other alternatives along the property line, farthest
from the intersection. In such cases, agencies typically reserve the right to require directional
connections (i.e., right-in/out, right-in-only, or right-out-only) or nonconforming corner properties to
share access with abutting properties.
While restricting the access to right-in/right-out, it is equally important to provide an appropriate
channelization to restrict prohibited movements as insufficient channelization could provide enough
space to invite prohibited turns. Thieken and Croft (2004) carried out a study in Ohio on the evaluation
final report: page 10 of 67
Figure 4. Restricting driveway to right-in/right-out in the functional area of intersection
of characteristics that impact violation rates at right-in/right-out driveways. Their research focused
exclusively on right-in/right-out driveways with no center median on the highway to prohibit left-turns.
They collected data at seven right-in/right-out sites and performed linear regression analysis to evaluate
the nature of relationships between violations and right-in/right-out driveway and site features. Their
analysis results were not conclusive but pointed some important characteristics as causes of violations
including the shape and size of the raised island, existence of vehicle storage on the arterial, existence of
delineators on the island, the volume of traffic on the arterial, visibility of alternate legal left-in/left-out
facility and signage at the driveway.
REVIEW OF PRACTICE
An attempt was made to identify and review access management documents (including manuals and
publications) for all states in order to determine different standards, guidelines, and/or rules for
controlling turning movements at driveways (e.g., when to allow/restrict driveways; how to control
them; and design standards for driveway width, spacing, and corner clearance). Such information was
found on-line for 31 states. While most of these states have provided their design standards for
driveways, only a few appear to have implemented a formal turn-restriction policy. A summary showing
the number of states that provide the required information, including their criteria and design
standards, is provided in figure 5 with more detail in figure 6. Detailed information from all available
Functional area of Intersection
final report: page 11 of 67
Access management
documentation related to
driveway operation
3. Driveway Spacing
4. Corner Clearance
2. Driveway Width
1. Driveway Types
Criteria
Driveway types include* (23)
Right in/out only
Full access
Other restrictive access combinations
* See next page for details
Driveway width criteria (24)
Driveway type (Residential,
Commercial or Industrial) (12)
Singe unit vehicular volume (2)
One-way and two-way entrances (4)
Trip/day and trip/hour or driveway
volume (3)
Driveway spacing criteria (27)
Speed (16)
Access class (5)
Access class with
speed (2)
Access class with median type (2)
No of access locations per mile (1)
Area type (1)
Corner clearance criteria (17)
Speed (8)
Access class (3)
Position of intersection and access
allowed at the driveway (2)
Signalized and unsignalized intersections
(2)
Rural/urban areas (1)
Specifying rules for corner clearance (1)
Not addressed (7)
Not addressed (6)
Not addressed (3)
Not addressed (13)
States with
documentation found
online (30)
States with no
documentation found
online (20)
Range of driveway width
Min : 9 – 26ft
Max: 16 – 48ft
Range for corner clearance
Min : 30 – 460ft
Notes:
All the values in parenthesis show number of states.
Counts for number of states in every criterion are
independent of each other.
Figure 5. Summary of Turn Restriction Policies
Range of driveway spacing
Min : 100 – 1500ft
Min : 80 – 430ft
[20 – 70mph]
[3 – 6]
final report: page 12 of 67
Not addressed (7) Addressed (23)
Guidelines for Driveway Types:
Right in/out only
Left turns
Full access
Guidelines for
Right in/out only (17)
Guidelines for
Left Turns (19)
Channelization (raised islands,
medians)
Pavement markings, signs and
channelization
If sufficient corner clearance, non-
traversable median to prevent left
turns
Geometric design and
channelization
In multilane urban arterial if ADT
> 30,000 vpd, (a median island
should be installed for right turn
in/out only).
If access connections are to be
located within the functional area
due to limited property frontage,
access may be restricted to right
in/out only.
If future traffic volume could
warrant installing a signalized
spacing requirements cannot be
met, the left turns may be closed
at that time in future.
Appropriate median cross-
over and channelization
Storage lanes by checking the
volume warrants for LT lane
(on highway)
Appropriate median opening
Dedicated LT lanes (on
highway)
2-way LT lanes (on highway)
Left turns allowed if in the
opinion of the department
such left turns can be
reasonably accomplished.
Highway infrastructure
improvements for safe and
efficient traffic operations
when there are high turning
traffic volumes.
Guidelines for
Full Access (7)
Appropriate median cross-
over spacing, auxiliary lanes
on the highway, adequate
channelization and dedicated
lanes for all movements.
Full access allowed with
detailed design (provided by
DOTs) with median cross-
overs on divided state
highways.
On divided highways, full
access can be allowed if there
is an approved full movement
median opening at the site.
Notes:
All the values in parenthesis show number of states.
Refer to detailed spreadsheet for further details.
1. Driveway Types
Figure 6. Summary of Guidelines for Driveway Types
final report: page 13 of 67
state documentation including turn restriction guidelines and design standards of driveways is provided
in appendix 1. A summary of those materials follows.
Colorado suggests restricting certain turning movements at driveways by channelized islands if the
driveway volume is predicted to exceed 100 DHV (design hourly volume). Left-turns are allowed on an
undivided highway by the approval of the permitting authority.
Delaware and Kansas do not address when to provide right-in/out only driveways but recommend
proper channelization to control these types of driveways. Delaware allows left turns where the design
meets all safety requirements (although it’s not clear what these include). It also recommends median
crossover and channelization to control for both right and left turns. Kansas also suggests modifications
in median crossovers to accommodate projected traffic movements.
Seven states including Florida, Idaho, Kentucky, North Carolina, Texas, Utah, and Virginia have similar
guidelines for right-in/out-only driveways. According to these states, when sufficient corner clearance
cannot be provided or if access connections have to be located within the functional area due to limited
property frontage, the access may be restricted to right-in/out only or other limited movement
treatments. Texas addresses this issue along with connection spacing. According to Texas guidelines, it
is also important to maintain adequate connection spacing and if it cannot be achieved then lesser
spacing for a shared access with an abutting property may be allowed. In case of no other alternatives,
Texas allows the access location along the property line farthest from the intersection but to ensure
safety under these conditions, it recommends allowing only the right-in/out turning movements if
feasible.
The Access Management Manual (TRB, 2003) provides similar guidelines in this context. It suggests that
there should be sufficient corner clearance to separate access connections from roadway intersections.
In case of no other alternatives, it recommends allowing the access connection as far as possible from
the intersection but in these cases agencies typically reserve the right to restrict driveways as right-
in/out, right-in only or right-out only.
According to Indiana, major driveways into developments such as shopping centers should be
constructed to prevent cross traffic movement of internal traffic within 100 ft from the highway edge of
final report: page 14 of 67
pavement. This may be accomplished by the use of a raised island. In context of left-turns, the state
guidelines recommend dedicated left-turn lanes on the driveway and left-turn deceleration lanes on the
highways for required level of service above “C.” For high volume traffic generators such as shopping
centers, industrial plants, industrial parks, residential projects, and similar developments may have a
median crossover desirable.
Iowa suggests that median openings should not be permitted except to accommodate large traffic-
generating facilities such as large shopping centers or industrial plants. Median openings may be
permitted in these instances if adequately justified (again, undefined) to account for turning
movements.
Maryland recommends using commercial right-in/right-out driveways on all divided highways with
posted speeds above 40 mph. For urban street environments where posted speeds are 40 mph or lower
and a narrow raised median separates the directional highways, it allows use of other commercial
driveways as long as appropriate signing is provided to discourage errant movements.
Minnesota addresses this issue for existing roadways and recommends limiting the entrance to right-
in/right-out only, unless weaving or other traffic operations indicate the need for further restrictions on
turning movements (e.g., right-in only or right-out only). It also suggests limiting access to right-in/right-
out movements on planned highways where a median is to be constructed.
New Jersey provides two scenarios to restrict left turns: if future traffic volumes warrant installing a
traffic signal and signalized spacing requirements cannot be met, at such time left-turn access may be
closed; and if an undivided highway becomes divided as a condition of the access permit, left-turn
access may be closed. In both cases, access should be closed for left-turns in accordance with the
standards provided by the New Jersey Access Management Code.
New Mexico suggests restrictions to full left-turn access when there are issues related to safety or
operational deficiencies that would be expected if a full access median was implemented. Geometric
design and channelization should be used to restrict undesirable movements.
final report: page 15 of 67
According to Ohio, left-turn movements shall not be permitted if a median is already established and the
opening of the median would not provide, in the determination of the Department, any significant
operational or safety benefits to the general public or would be counter to the purpose of the median
construction and the continued function of the highway at the category assigned to it.
Pennsylvania implements turn restrictions if the improvements that would be required at a driveway to
achieve acceptable levels of service cannot be provided due to constraints, or if there is a history of high
crash rates due to left-turning vehicles. For high and medium volume driveways, channelization islands
and medians shall be used to separate conflicting traffic movements into specified lanes to facilitate
orderly movements for vehicles and pedestrians.
Vermont permits one or both left-turn movements at the access point if the applicant establishes to the
agency's satisfaction that left-turn movements would not create unreasonable congestion or safety
problems, or lower the level of service below the agency’s policy.
In Washington, all private access connections are for right-turns only on multi-lane facilities unless there
are special conditions and the exception can be justified.
Wyoming’s recommends installing a median island on multi-lane urban arterials if the ADT is more than
30,000. In this case, direct access would be right-in/right-out only and they should be provided with
right-turn deceleration lanes.
Several states, including Georgia, Maine, Michigan, West Virginia, and South Dakota generally indicate
that raised islands or channelization are effective in controlling right-in/out-only driveways. On the
other hand, left turns can be accommodated with proper median opening design. Maine also suggests
two-way-left-turn-lanes onto a mobility arterial to accommodate left-turns.
From the review of state practices, it can be concluded that there are not unique criteria that are
followed by all or most states for right-turn-in/right-turn-out restrictions in their access management
policies. Most of the states that address this issue provide different criteria to restrict turning
movements, which include level of service, average daily traffic, and crash history. A few states which
provide somewhat similar scenarios recommend providing right-in/out only driveways when there is
final report: page 16 of 67
insufficient corner clearance and there is no other alternative. This practice is also recommended by the
Access Management Manual (TRB, 2003). Almost all the states which provide any guidelines in relation
to turn restrictions recommend proper channelization to restrict undesirable movements into or out of
the driveways, and adequate median crossover design to accommodate left-turns if required. Even the
states which have developed criteria related to access control are often vague with respect to defining
specific thresholds that are appropriate for when access should be restricted.
ANALYSIS OF SAFETY AND OPERATIONAL IMPACTS OF TURN RESTICTIONS IN MICHIGAN
In the context afforded by the review of the literature and state practice in restricting turning
movements at development access points, several sites in Michigan were identified for detailed study.
As noted previously, the latter consisted of an analysis of crash histories before and after turning
restrictions were implemented and an analysis of operational impacts. The actual study sites were
selected by MDOT and were then supplemented with a selection of similar sites for comparison
purposes. Crash analysis was then done on all sites. Operational impacts were studied using a micro-
level traffic simulation software package—VISSIM. The point of these two analyses was to identify when
turning restrictions should be implemented from traffic safety and operations perspective. More details
on these two approaches, as well as the results, are provided in the following sections.
SITE SELECTION
A total of eleven (11) sites with recently-implemented access control (e.g., left turns in/out prohibited)
were identified by MDOT, out of which nine (9) were selected for detailed study. The list of project sites
is provided below and more-detailed descriptions are in appendix 2.
Site 1: MSU Federal Credit Union, W. Saginaw Street, Lansing
Site 2: Walgreens, W. Saginaw Street and Creyts Road, Lansing
Site 3: Rite Aid, SE corner of M-36 and Dexter Road, Brighton
Site 4: Walgreens, M-21 and Linden Road, Flint
Site 5: Krispy Kreme, M-21, Flint
Site 6: Tim Hortons, M-57, Clio
Site 7: BP Gas Station and fast food restaurants, M-21, Lennon
Site 8: National City Bank and Advance Auto, US-12 (Chicago Road) and Michigan Avenue,
Coldwater
Site 9: Family Video, M-66 (Capital Ave) and Emmett Street, Battle Creek
final report: page 17 of 67
The main objective of the preliminary site visits was to get a general sense of problems at individual
sites, and to perform preliminary data collection. Manual data collection forms (see appendix 3 for
details) were developed and modified to fit specific sites based on these observations. All data were
collected during February-April, 2008. During follow-up visits, the following types of data were
collected:
1) manual traffic counts using data collection sheets;
2) traffic volume and turning counts using counters (Traffic Data Collector, TDC-12, Jamar
Technologies, Inc.); and
3) video-tape recordings.
These data were used to better understand what was going on at the site (e.g., were motorists ignoring
turning restrictions) and provide the data necessary to examine operational impacts of the various
turning treatments at geometrically different sites using the traffic simulation software (VISSIM).
The sites are presented and discussed one-by-one in the following paragraphs. In each instance, a
picture of the MDOT-identified site is presented along with a similar site. Initially, it was thought that a
classic “before-after with control” study could be done on all of the sites. As work progressed,
numerous problems cropped up including differences among the selected sites, difficulty in identifying
true control sites, unknown time windows for changes in access, unknown prior land uses, and
significant variation in variables that could be used to classify sites (e.g., ADT). Thus, the sites selected
are termed as “similar” (rather than “control”), and the crash analysis is qualitative rather than
statistical in nature.
SAFETY IMPACTS
As just noted, sites are presented one by one and introduced with some general comments. In each
case the sites were identified and an indication of when the access control change was implemented.
Electronic crash records were then retrieved from the statewide crash database. Once these crashes
were identified, hard copies were also retrieved so that a better understanding of the crash
circumstances could be obtained (i.e., through review of the crash-scene sketches and hand-written
comments). More detail is provided for the first site in order to better illustrate this procedure.
final report: page 18 of 67
Site 1: Walgreens, W. Saginaw Highway and Creyts Road, Lansing (corner site; before intersection)
(a) study site (b) similar site
The first site is located in the southwest (SW) quadrant of Saginaw Highway and Creyts Road in Lansing.
The land use was changed to Walgreens in 2004 with a full access driveway on Creyts Road and a right-
in/right-out-only driveway on Saginaw. The right-in/right-out driveway is provided with a raised island
and narrow driveway lanes to prohibit left turns (in and out), but drivers were observed using this
driveway to turn in and out of the development illegally. There is a right-turn auxiliary lane at the
intersection. ADT on Saginaw is 33,200 vpd according to 2007 traffic counts which is considered to be
high volume (FHWA’s definition of high volume is adopted here: ADT>15,000 vpd). Corner clearance for
this driveway is 209 ft which is below the MDOT’s stated minimum standard of 230ft. However, the
driveway is located at the farthest point (on the property) from the intersection.
The “similar site” is located in the SW quadrant of Pennsylvania and Michigan Ave in Lansing. The
development is a pharmacy of almost the same size as that of the study site. Driveways on both the
roads providing access to the development are full access. Pennsylvania Ave (with the driveway of
interest) is a busy street (ADT=19,857 vpd) as it serves as a major route for traffic to Sparrow Hospital
and Eastern High School. This site seemed somewhat comparable to the study site.
The “window” for tracking crashes is 2000-2007 (3-4 years on either side of the year of the change). As
part of the crash analysis, driveway-related crashes were broken out of the total crash frequency and
reported in the following figures and summary tables. In the bar charts driveway-related crashes are
reported and also shown as a fraction of total crashes in the area. The analysis of this site showed
crashes involving left-in and out movements before 2004. The driveway-related crash frequency was
Full-access driveway
on control site
Right-in/Right-out
driveway on study site
final report: page 19 of 67
found to be 3 crashes in four years at the driveway on Saginaw. As all crashes reported at the driveway
involved left-turning movements, it can be assumed that the driveway on Saginaw Hwy might not been
restricted earlier because no evidence of turning violations was found on the crash reports.
0 0 0 0 0 0
1/3
2/3
0
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er o
f D
riv
ew
ay-R
ela
ted
Crash
es
Saginaw
0
1/4 1/4
0 0
3/113/9
1/9
0
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
YearN
um
ber o
f D
riv
ew
ay-R
ela
ted
Crash
es
Pennsylvania
Ave
* The number in the numerator is the number of driveway-related crashes; the denominator is total crashes
The other crashes at the site (i.e., those not driveway-related) were primarily rear-end crashes. Further
details can be found in appendix 4. Considering the above, it appears that restricting the access to right-
in/right-out has contributed to improving the safety at Saginaw Hwy by reducing the number of crashes.
During the data collection, it was noted that turning movements are controlled by a small channelization
island at the driveway entrance to provide restrictions for left-turn movements; however illegal left
turns (in and out) were made frequently although presumably not as often as they would have been
without the channelization. There was no sign on the island indicating turning prohibitions. Thus, the
reduction in turning-related crashes is in spite of the prohibited maneuvers.
Site Type of Access
Adjacent Road
Time Span
Total Crashes on the
Adjacent Road
Driveway Related Crashes
# %
Study Site 1 RIRO Saginaw Hwy Before 2004 16 3 18.8
After 2004 15 0 0
Similar Site Full Access Pennsylvania Ave 2000-2007 58 9 15.5
Study Site 1 Similar Site 1
* After Before
final report: page 20 of 67
Site 2: MSU Federal Credit Union, W. Saginaw Highway, Lansing (mid-block site)
(a) study site (b) similar site
This is a mid-block site, well beyond the influence area of the next downstream (signalized) intersection.
The driveway is a main driveway leading to a commercial area (not just the MSU FCU). The driveway is
restricted by a small channelization (and signed for outbound traffic) to restrict left turning movements.
The information about the changes that occurred to the site was neither found by MDOT nor in the UD-
10 reports. The channelization seems to be insufficient to deter drivers from making left turns (in and
out) as they were frequently observed to run over (literally) and around the island during the site visits.
The ADT on Saginaw is 28,100vpd and, so, classified as a high-volume site.
The similar site is a Comerica bank at a mid-block location on N. Grand River Avenue (near Bardaville
Drive) in Lansing. ADT on Grand River is 17,100vpd, less than on Saginaw but still comparable in the
sense that it is also “high volume.” The driveway is a full-access, allowing both left turns in and out and
also provides access to other land uses.
0 0 0000000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er o
f D
riv
ew
ay-R
ela
ted
Crash
es
1/2
0 1/30
1/1
00
1/1
0
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er
of
Dri
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ela
ted
Cra
sh
es
Right-in/Right-out
driveway
on study site Full access
driveway on
control site
Study Site 2 Similar Site 2
final report: page 21 of 67
Site Type of Access
Adjacent Road
Total Crashes at the
Adjacent Road
Driveway Related Crashes
# %
Study Site 2 RIRO Saginaw Hwy 9 0 0
Similar Site 2 Full Access Grand River Ave 7 3 42.8
Even with the insufficient channelization and frequent left-turning violations which could be safety
hazards, no crashes were reported at this driveway in the past eight years. However, a few rear-end
crashes and other driveway-related crashes occurred in the vicinity of this site. As frequent left turning
violations were observed at the site along with the vehicles running over the island, the insufficient
channelization at this driveway could be a potential safety hazard. The analysis of the similar site
showed 7 crashes at this site in the past eight years, of which 3 were driveway-related involving the left-
out movement from the driveway (despite the lower mainline volume).
Site 3: Rite-Aid Pharmacy, M-36 (E Main Street) and Dexter Road, Pinckney (corner site; after intersection)
(a) study site (b) similar site
This site is located in the SE quadrant of Dexter St and M-36 (Main St) and was changed to a Rite Aid
Pharmacy in 2003. The site is in a small town so the traffic volume is not high (ADT=11,210 vpd on Main
St). While this is a corner site, the driveway is AFTER the intersection and, so, different from site 1. The
driveway is restricted to right-in/out-only and close to the intersection (although at the farthest point on
the property).
Full access driveway
on control site Right-in/Right-out
Driveway on study site
final report: page 22 of 67
The similar site is at the intersection of Genesee and Mt Morris Rd in Mt Morris and is also a Rite
Aid Pharmacy. The driveway is full access. It is also located in a less urbanized area. The ADT on
Mt Morris Road is 5,390 vpd and, so, reasonably comparable to the study site.
0 0 0 0 0 00
1/1
0
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er
of
Dri
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ay-R
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ted
Cra
sh
es E Main St
0 0 0 0 0 0000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
YearN
um
ber o
f D
riv
ew
ay-R
ela
ted
Crash
es
Site Type of Access
Adjacent Road
Time Span
Total Crashes at the
Adjacent Road
Driveway Related Crashes
# %
Study Site 3 RIRO E Main St Before 2003 2 1 50
After 2003 11 0 0
Similar Site 3 Full Access Mt Morris Rd 2000-2007 14 0 0
The crash analysis at the study showed that there was only one driveway-related crash in the
before period and none during the after period. The similar site had no driveway-related crashes
during the entire time window.
As far as the type and severity of crashes is concerned in the vicinity of the site, some rear-end crashes
had been reported every year at E Main St while on Dexter St. In addition to the rear-end crashes, angle
crashes were also observed. Most of the crashes at the site were found causing property damage only.
The lack of driveway-related crashes at this site implies that turning restrictions may not be so
critical in lower-volume situations and/or when the development is located after the intersection,
notwithstanding the other crashes that are occurring.
Similar Site 3 Study Site 3
Before After
final report: page 23 of 67
Site 4: Walgreens, Corunna Road (M-21) and Linden Road, Flint (corner site; after intersection)
(a) study site (b) similar site
This site is located in the NW quadrant of Corunna and Linden Roads in Flint. Before 2003, the
development was a bank and the driveway at Corunna Rd was full access and closer to the intersection
than it is now. The current development (Walgreens) has a restricted (right-in/out-only) on Corunna
Road. The restricted driveway is signed to further “enforce” the channelized driveway: “Right Turn
Only” and “Do Not Enter” signs were used to permit outbound right turns and to restrict outbound left
turns respectively; another “Do Not Enter” sign was used to restrict inbound left turns. The ADT on
Corunna is 18,400 vpd,
The similar site is a Walgreens at E Atherton Road and S Dort Highway in Flint. In this instance the
driveway is full access. Dort has an ADT of 20,800.
2/15 2/11
1/7 1/8 1/8
0 000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Corunna
0
1/7 1/7 1/3 1/8 1/6
0 00
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Dort Hwy
Full access driveway
on control site
Right-in/Right-out
driveway on study site
Nu
mb
er
of
Dri
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ted
Cra
shes
Nu
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er
of
Dri
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Cra
shes
Year Year
Before After
Study Site 4 Similar Site 4
final report: page 24 of 67
Site Type of Access
Adjacent Road
Time Span
Total Crashes at the
Adjacent Road
Driveway Related Crashes
# %
Study Site 4 RIRO Corunna Rd Before 2003 33 5 15.1
After 2003 29 2 6.9
Similar Site 4 Full Access Dort Hwy 2000-2007 53 5 9.4
In this instance, results showed a significant number of driveway-related crashes involving left-out
movements over the period. After 2003, when the site was changed to Walgreens and presumably the
driveway at Corunna Rd was restricted to right-in/right-out, there was a decrease in crashes at the
restricted driveway. Since the land use was known to have changed, ITE trip generation models were
used to check the likely changes in driveway volumes. The former land use was a bank which, according
to the trip generation software, would have almost three times as much driveway-turning volume.
Thus, some of the decrease in driveway crashes could also be due to the decrease in the turning
volumes and related conflicts. A separate examination (not shown) of the driveway on the cross street
indicated that the crash frequency at the full access driveway on Linden Rd didn't decrease and in fact
after 2003 both left-in and out movements from this driveway had been causing crashes. Comparison of
the trend at the study site (Corunna Road) to that at the similar site (Dort Highway) showed that the
latter had relatively similar performance over time. In general then, the evidence at this site points to
potentially mixed results relative to the efficacy of changing the access control at the study site.
However, it is clear that, at a minimum, there was no increase in crashes as a result of the change.
final report: page 25 of 67
Site 5: Krisy Kreme, M-21 (Corunna Road), Flint (mid-block site)
(a) study site (to the left) and (b) similar site (to the right)
This is a mid-block site where both the study and similar sites are on the same segment of highway and
not too far apart. Notwithstanding potential rush-hour directional shifts, the traffic conditions should be
quite similar. The study site was changed to Krispy Kreme in 2003. The driveway of this site is properly
restricted with raised island and signage to prohibit left turns (ins and outs). Some violations of the
turning restrictions were noted during data collection. This similar site is located just about 1000 feet
away on the opposite side of the road. The development at the similar site is a fast-food restaurant
(Wendy’s) and has been present since at least 2001 (verified by information found in the UD-10 reports).
According to ITE trip generation models, the generated traffic for both land uses is comparable but a
little higher in PM at fast-food restaurant. The driveway allows full access. ADT on Corunna Road is
about 27,200 and can be considered as a high volume arterial (according to FHWA definition of high
volume ADT 15,000).
Full access driveway
on control site
Right-in/Right-out
driveway on study
site
final report: page 26 of 67
0 0 000
1/4
000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er
of
Dri
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ay-R
ela
ted
Cra
sh
es
1/11 1/10
000
1/7
000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er
of
Dri
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ay-R
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ted
Cra
sh
es
Site Type of Access Adjacent
Road Time Span
Total Crashes at the
Adjacent Road
Driveway Related Crashes
# %
Study Site 5 RIRO Corunna Rd Before 2003 9 1 11.1
After 2003 20 0 0
Similar Site 5 Full Access Corunna Rd 2000-2007 51 3 5.8
[check numbers above and in bar charts]
The crash analysis showed just one (1) left-turning-related crash in the past eight years at the driveway
at the study site, and that was during the after period. Similarly, there really are only a few turning-
related crashes at the similar site. The crash analysis at this site shows quite neutral impacts of changing
the access control.
Study Site 5 Similar Site 5
Before After
final report: page 27 of 67
Site 6: Tim Hortons, M-57 (Vienna Road), Clio (mid-block site)
(a) study site (to the right) and (b) similar site (to the left)
The driveway providing access to this mid-block site is restricted for outbound left turns only. Thus, this
restriction is different from the other study sites. (However, there were no such restrictions for
adjacent developments.) In addition, the information regarding land-use change that occurred at the
site was not found in the accessible resources (i.e., it is not clear when access restrictions changed).
Some prohibited left turns were observed during data collection periods. The similar site is located on
the same road ~ 750 ft away from the study site. The driveway providing access to the similar site is
restricted for left-turn movements (inbound and outbound). The ADT on Vienna Road is 38,140.
No driveway-related crash was reported at the study site in the past eight years, and only one was noted
at the similar site. Moreover, the latter involved an illegal “left” turn but appeared (from the UD-10
sketch) to involve a vehicle attempting to go more-or-less straight across the highway to a land use on
the other side (a somewhat atypical movement).
Because of the different access restrictions as well as the lack of driveway-related crashes, neither the
study nor the similar site are really comparable to the other sites. However, the paucity of crashes in
Right-in/Right-out
driveway
Prohibited Driveway
for outbound left turns
on study site
final report: page 28 of 67
and of itself suggests that turning restrictions at mid-block locations (even on high volume streets) may
not be critical from a safety perspective.
0 0 0000000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
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of
Dri
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ay-R
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ted
Cra
sh
es
0 0
1/4
000000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
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of
Dri
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ted
Cra
sh
es
Site Type of Access Adjacent
Road
Total Crashes at the
Adjacent Road
Driveway Related Crashes
# %
Study Site 6 Restricted for left-out Vienna Rd 17 0 0
Similar Site 6 Full Access Vienna Rd 14 1 7.1
Site 7: BP Gas Station w/convenience market and fast-food restaurants, M-13, Lennon (corner site; before intersection)
(a) study site (b) similar site
Study Site 6 Similar Site 6
RIRO driveway on
study site
Full access
driveway on
control site
final report: page 29 of 67
This site is a mixed-use development consisting of a gas station, convenience market, and two fast food
restaurants. The land-use was changed to the gas station in 2004. ADT on M-13 is 4,480, a lower-
volume site. This site was located in a somewhat rural area with no major adjacent developments. The
gas station was a corner mixed development. The driveway being studied was restricted to a single lane
right-in/out-only driveway with a large island channelization. There were few illegal left turns noted
during the site visit.
The similar site was a Speedway gas station and convenience store at the corner of Center and Bristol
Roads in Burton. The site has contained these land uses since at least 2001 and is full-access. The ADT
on the adjacent street was 11,893, appreciably higher than the study site but still under the FHWA figure
for being deemed “high volume.”
0 0 0000000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
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of
Dri
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ela
ted
Cra
sh
es
1/3 1/5 1/3
3/5
1/2
3/4
1/51/3
0
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
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of
Dri
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ted
Cra
sh
es
Site Type of Access
Adjacent Road
Time Span
Total Crashes at
the Adjacent
Road
Driveway Related Crashes
# %
Study Site 7 RIRO M-13 Before 2003 4 0 0
After 2003 1 0 0
Similar Site 7 Full Access Center Rd 2000-2007 30 12 40
Results of the analysis showed no driveway-related crash in the past seven years at this site. Even in the
vicinity of the site, a very low crash frequency was observed before and after the site was changed. By
comparison, the similar site had at least one driveway-related crash every year on the Bristol Road. The
analysis showed 12 driveway-related crashes in the past eight years. It was also observed that most of
Study Site 7 Similar Site 7
Before After
final report: page 30 of 67
the crashes involved the left-out movement from the driveway and some of them involved cross
movement from this driveway to a driveway across the street. It appears that the proximity of this
driveway to the intersection and the cross-traffic maneuvers from this driveway to the driveway across
the street are causing problems at this site.
Overall, while it appears that the crash history at the study site reveals nothing positive (other than
restricting access at relatively low volume locations does not degrade the safety), the examination of the
unrestricted access at the similar site shows some continuing safety-related problems. Note, however,
that the ADT is considerably higher than the study site and is approaching the definition of “high
volume.”
Site 8: National City Bank and Advance Auto Parts, US-12 (Chicago Road) and Michigan Avenue, Coldwater (corner site; before intersection)
(a) study site (b) similar site
The development at this site consists of a bank and an auto parts store. The information regarding the
changes at the site was not found through readily-available sources. However, the bank at this site
seemed to be new, as the latest online image available (above) does not show the bank. The driveway
on the Chicago Rd is “right-in only” and the ADT is surprisingly high at 17,710 vpd. The similar site is a
combination of CITI Financial and a Subway store near the intersection of Davison and Belsay Roads in
Burton. The driveway of interest provides unrestricted access to the site and the ADT is 9,648.
Full access
driveway on
control site
Right-in only
driveway on
study site
final report: page 31 of 67
0 0 0000000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er o
f D
riv
ew
ay-R
ela
ted
Crash
es
0 0
1/5
0
1/9
00
1/10
0
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er o
f D
riv
ew
ay-R
ela
ted
Crash
es
Site Type of Access
Adjacent Road
Total Crashes at the
Adjacent Road
Driveway Related Crashes
# %
Study Site 8 Right-in only US-12 43 0 0
Similar Site 8 Full Access Belsay Rd 45 3 6.6
There was no clear evidence that there were any crashes related to the site driveway although the time
periods examined may not have actually included the site in its new configuration. While the ADT is
high, the turning volumes from the site over time were probably quite low as the prior use (see photo)
was not very intense. However, the full-access drive at the similar Belsay Road site experienced some
crashes.
Similar Site 8 Study Site 8
final report: page 32 of 67
Site 9: Family Video, M-66 (Capital Avenue) and Emmett Street, Battle Creek (corner site; before intersection)
(a) study site (b) similar site
This site is a video rental store and located at the SE quadrant of M-66 (Capital Avenue) and Emmett
Street in Battle Creek. Examination of hard copies of crash reports (forms UD-10) for this site revealed
that the development was a bank until 2006 and then changed to Family Video. The ADT on M-66 is
14,800 (while not exceeding the definition for a high-volume road, it’s probably “close enough). It is not
totally clear when the driveway was changed from full-access to its current “right-in-only” status—it was
probably at least in 2006 and maybe earlier than that (see discussion below). Note that the access
control at this site is somewhat different from the others in that a right-turn-out is not permitted.
Moreover, the channelization seems to be more emphatic—e.g., (illegal) left turns appear to be much
harder to make than at other sites.
The similar site is the same type of video store on Center Road near Atherton Road in Burton. The ADT
on Center is 15,083 and the driveway provides full access.
Over the study period (see figure and table on the next page), the crashes that occurred at the study site
involved both left-in and right-in movements. As some crashes involved left-in movements (prior to
2006) it is not clear whether the driveway was channelized at that time (and the turns were prohibited)
or the driveway was full access. In any event, no driveway-related crashes were reported at this
driveway after 2004. So, it would appear that the turn restriction has been successful at the study site.
Full access
Driveway
Right-in only
Driveway
final report: page 33 of 67
The crash history at the similar site (with full access) shows occasional driveway-related crashes
throughout the examination period, including at least two which involved left-turning vehicles.
0 0 000
1/9
0
2/5
0
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er o
f D
riv
ew
ay-R
ela
ted
Crash
es
2/9
0
1/3
0
1/3
0000
1
2
3
2000 2001 2002 2003 2004 2005 2006 2007
Year
Nu
mb
er o
f D
riv
ew
ay-R
ela
ted
Crash
es
Site Type of Access Adjacent
Road Time Span
Total Crashes at
the Adjacent
Road
Driveway Related Crashes
# %
Study Site 9 Right-in only M-66 Before 2006 37 3 8.1
After 2006 2 0 0
Similar Site 9 Full Access Center Rd 2000-2007 58 4 6.9
Discussion and Conclusions
As it turns out, there was more variation in the types of sites than had been expected—sites varied by
location relative to the intersection, land use for the development, the type of access control employed,
the length of before and after periods, and ADT, among other things . Moreover, it was quite difficult to
find what might be considered “pure” control sites for comparison purposes. Thus, the analysis of the
safety-related (crash) impacts of restricting access control is qualitative rather than statistical. Those
points notwithstanding, the analysis does lead to some reasonable conclusions. These will be used with
the findings from the simulation studies to develop guidelines for controlling access.
First, a summary table is presented which covers the crash analysis for all nine sites. Then a list of
conclusions and discussion is provided.
Before After
Study Site 9 Similar Site 9
final report: page 34 of 67
Table 3. Summary of crash analysis results for all study and similar sites
volume category
site ADT type of control corner
clearance relation
to corner
driveway-related crash history
before after
corner sites
high1
site 1 33,200 RIRO 209 before 3 0
similar site 1 19,857 full 170 before 92
site 9 14,800 RIRO 224 before 3 0
similar site 9 15,083 full 150 before 42
site 8 17,170 RI-only 252 before 0 0
similar site 8 9,6483 full 275 before 32
site 4 18,400 RIRO 224 after 5 2
similar site 4 20,800 full 150 after 52
low- medium
site 7 4,480 RIRO 229 before 0 0
similar sIte7 11,893 full 100 before 122
site 3 11,210 RIRO 186 after 1 0
similar site 3 5,390 full need # after 0
mid-block sites
high
site 2 28,100 RIRO N/A N/A 0 0
similar site 2 17,100 full N/A N/A 32
site 5 27,200 RIRO 1824 N/A 0 1
similar site 5 27,200 full 1854 N/A 35
site 6 38,140 RIRO + LI N/A N/A 0 0
similar site 6 38,140 RIRO N/A N/A 1
1 high volume: ADT>15000vpd
2 spread over entire period 3 does not meet high-volume criterion—included because similar to study site on other grounds 4 unsignalized access road/development driveway 5 distribution not even over period—more crashes earlier but no more than 1/year
At the high-volume (ADT>15,000 vpd) corner sites there appears to be a reduction of driveway-related crashes when access control is changed from full access to right-in/right-out. For the similar sites, there were fairly constant numbers of annual crashes. However, the crash frequencies for the sites considered was not high to start with. At best, it would appear that the crash reduction would be one crash/year or less. This finding is reasonably consistent with the literature and the crash reduction factors shown in table 2.
It is not clear how corner clearances or other geometric differences among the sites impacted the crash frequencies.
Significant changes in crash severity were really not apparent.
For the low-medium volume corner sites, there did not appear to be much of a problem with crashes during the before or after periods.
final report: page 35 of 67
The crash frequencies at the mid-block sites did not change appreciably since there was little evidence of a problem in the before period. It should be noted, however, that the sites reviewed all experienced relatively low turning volumes—i.e., driveways serving major malls were not in the mix.
During the examination of several of the high-volume similar (corner) sites, it was observed that there was significantly more involvement of outbound left-turning vehicles than inbound lefts in crashes and that right-turning vehicles were seldom, if ever, involved.
The turning restrictions associated with access control were observed to be violated in many instances. The existing channelization and/or signing (both of which vary considerably) is not completely effective in preventing the prohibited turning movements.
To summarize the findings of the safety/crash analysis: based on an analysis of a variety of existing sites
where access control has been changed, there is some evidence that access control will result in lower
crash frequencies in some instances, but the crash reduction when modest turning volumes are involved
is relatively low.
OPERATIONAL IMPACTS
While the safety review indicated that there were some modest savings due to crash reduction for
higher-volume corner locations on higher-volume streets, one of the remaining questions is whether
there are travel delay impacts which are consistent: Do vehicle delays that are associated with different
access control scenarios “warrant” restricting access control?
For this part of the investigation, the traffic simulation model VISSIM was used to simulate operations at
the various sites, and then conditions (e.g., street volume, turning volume, corner clearance) were
varied to show when operations became untenable. Synchro (a Highway Capacity Manual [HCM]-based
software used to evaluate intersection operation) was also used to assess existing conditions at each
site and to optimize signal timing to be used in the simulation model.
Basic Simulation Model and Assumptions.
The basic modeling process is described below.
Because of the variance in the number and use of lanes at the various sites, a total of eight VISSIM models were developed, six were for corner and two for mid-block sites. The corner sites were further grouped into two categories: four where the driveway is before the intersection and two where the driveway is after.
final report: page 36 of 67
In addition to the geometric layout and location of the driveway which were explicit in each model, four other factors were considered: corner clearance (CC), mainline volume (MV), driveway volume (DV), and left-turn-in and -out volume (LT). CC was defined as the distance in feet from the inside edge of the intersection to the (near) inside edge of the driveway. MV was defined as the volume in vehicles per hour (vph) on the main roadway adjacent to the study driveway. DV was defined as the driveway volume in vph entering and exiting the facility exclusive of the MV. LT was defined as the left turn in and out volume in vph. Even though LT is a driveway volume, it was considered as a separate variable.
Each of the variables was varied over a specified range and separate simulation runs were made for each combination for different kinds of access control. The ranges were defined to account for logical ranges for the types of development and roadway conditions encountered in the field. Traffic volumes were varied so that traffic operations would eventually break down. The ranges for the variables are: CC—150, 250, and 350 feet; MV—250, 500, 1000, 1500, and 2000 vph; DV—25 and 150 vph; and LT—10 and 50 vph.
The five access control scenarios were: (1) no driveway; (2) RT-in only; (3) RT-in/out only; (4) RT-in/out + LT-in; and (5) full access.
It was assumed that the driveway trips were passer-by trips, e.g., if they were traveling eastbound prior to turning into the development, they traveled eastbound upon exiting (right-turn in, right-turn out). Since there was no LT-out for RT-in/out + LT-in only driveway, the LT-out traffic in that case was assumed to leave the facility through a RT-out exit and was added to the mainstream traffic at the intersection.
After the basic model was specified, the models were calibrated to simulate the actual conditions as observed in the field. A separate VISSIM model was built for each site for the existing conditions of geometry, mainline and driveway volumes, and signal timings and phases. Since the major measures of effectiveness (MOEs) measured in the field were travel time and queue length, the average travel time and queue length outputs from the simulations were compared with the field data. The VISSIM input factors (e.g., vehicle performance—acceleration/deceleration rates, driver characteristics—percentages of different drivers, and lane-change behavior—aggressive or passive) were initially used as default values. The results obtained for the travel times and queue lengths using these default values were close to field observations. The VISSIM outputs were also checked against Synchro outputs (e.g., average delay and maximum queue lengths). The results obtained for this comparison were close, and thus the VISSIM models were considered to be reasonable to use for the project.
When mainline volumes (MV) were allowed to vary, it was necessary to make an assumption about what would logically occur on the other approaches to the intersection (this will impact overall intersection delay). Three cases were reviewed for the first model: Case 1—only the MV on the subject approach changes; Case 2—MV volume in both directions changes (proportionately) and Case 3—the MV for all approaches changes. After considerable discussion and examination of the output, Case 2 was selected as the most appropriate and logical case. Thus, all models were “exercised” using this assumption.
final report: page 37 of 67
In an actual situation where turns in to/out of a development are prohibited, traffic might make a U-turn after the intersection or somehow turn around and come back, and thus impact intersection delay. Such potential movements were ignored in the work presented here—the effects are expected to be minimal on the MOEs that were used.
Synchro was used to optimize signal timings for each increment of MV. These timings were then used in the VISSIM models.
Operational Analysis Using VISSIM.
Once the basic modeling construct was developed, the various models were adopted and run for the
various combinations of the key factors. For each model, the process for obtaining and displaying the
results from the VISSIM output is described below.
The primary criterion for prohibiting LT-in and -out traffic was the average delay (sec/veh) for these movements. Average delay equivalent to level of service (LOS) C or better was considered to be acceptable. The LOS criteria for unsignalized intersections provided by Highway Capacity Manual were used to define the threshold values. Graphs for average total delay and 50th percentile queue lengths were plotted to check the impact of MV and DV on the mainline traffic. However, since the motorists using the driveway had to stop for gaps in the mainline volume, the average delay of mainline volume was not the principal criterion. On the average delay graphs, the cutoff lines are shown for LOS C and D as red and blue lines, respectively. The line for LOS C indicates that if the average delay was below this line, the LOS was C or better. Similarly, an outcome above the blue line showed that the average delay was worse than LOS D.
The 50th percentile queue lengths were used to show the MV, DV, and LT combination for which the queue length will exceed the CC half of the time during the analysis period.
A summary of results for each model was prepared in a tabular format to show outcomes for the various combinations of CC, MV, DV, and LT (see the presentation for model 1 below for illustrations). These tables were prepared using the detailed graphs for average delay and 50% queue length and the criteria for left-turn restriction. These tables are helpful in understanding the trends and provide an overview of the impacts of ranges of different variables. Different symbols are used to indicate the combinations where left turns in and out are recommended to be restricted. The locations on graphs where left turns were recommended as “prohibited” are indicated by “,” and where left turns “may be allowed” by “.” Those points where the left-turn prohibition recommendations were not clear due to other factors (beyond what was defined in the analysis) are shown by “.” The prohibitions for LT-in as well as LT-out are shown together in the summary table.
Results for Model (site) 1 (lane configuration = 1 LT, 2 TH, and 1 RT—study site 1)
Site 1 is a fairly typical arterial roadway type often found in suburban areas, a basic 5-lane section which
widens at the intersection to accommodate a right-turn lane.
final report: page 38 of 67
The observed split by turning movement is:
Left Through Right 9.4% 77.6% 13.0%
In the following paragraphs, selected graphs illustrating various simulation results are presented. These
include average total delay (sec/veh) for the mainline traffic and the 50th percentile queue length (ft).
Average Delay (sec/veh) for Mainline Traffic.
The total average delay for the approach of interest was plotted against different increments of MV, CC,
and minimum and maximum values of DV and LT. In the following, the average delay graphs for CC =
150ft are shown with two different left-turning volumes (10 and 50 vph). (The average delay graphs for
CC of 250 and 350ft showed similar results, thus, not shown).
0
20
40
60
80
100
120
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160
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250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. T
ota
l D
ela
y a
t th
e S
tud
y L
eg
of
the
In
ters
ec
tio
n (
se
c/v
eh
)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Figure 7. Comparison of Average Total Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft and LT-in Vol=10vph
final report: page 39 of 67
0
20
40
60
80
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120
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250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. T
ota
l D
ela
y a
t th
e S
tud
y L
eg
of
the
In
ters
ec
tio
n (
se
c/v
eh
)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Figure 8. Comparison of Average Total Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
From the graphs, it can be seen that the average delay for the mainline traffic became worse than LOS C
as the MV approached 2000vph. However, the differences among the various turning restriction
scenarios (different column heights) are more apparent with the higher turning volumes. In the first
figure (LT-in=10vph), all of the vertical bars are about the same height whereas in the second (LT-in
=50vph) the scenarios that restrict left turns in and/or out perform better than those that do not. Since
driveway traffic and delay are dependent on the mainline traffic, they are used for developing the access
prohibition criteria.
Average Delay (sec/veh) for Driveway Traffic (vph).
The average delay for the driveway-related traffic was separated out and also compared to threshold
LOS criteria (for unsignalized intersections from the HCM). According to this criterion, LOS C
corresponds to an average delay of ~15-25 seconds, and LOS D to ~25-35 seconds. The average delays
were plotted separately for LT-in and LT-out driveway volumes against different increments of MV, CC,
and minimum and maximum values of DV and LT. In the following figures, the average delay graphs for
left turns in and out traffic are shown for CC of 150ft with LT volumes of 10 and 50 vph. Similar sets of
graphs were also obtained for CC = 250 and 350ft (shown in appendix 5) and used in the development of
LT-prohibition recommendations.
final report: page 40 of 67
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=150ft)
0
20
40
60
80
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120
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250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
rivew
ay (
se
c/v
eh
)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Figure 9. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
0
20
40
60
80
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120
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250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Figure 10. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
final report: page 41 of 67
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=150ft)
0
20
40
60
80
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120
140
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250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
Dela
y a
t th
e D
rivew
ay (
sec/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
Figure 11. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
0
20
40
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250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
Dela
y a
t th
e D
rivew
ay (
sec/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
Figure 12. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
D
C
D
C
final report: page 42 of 67
The graphs above (and those in the appendix) show that when the driveway delays are broken out and
considered separately, there are delay problems with some scenarios and they occur at mid-range to
higher values of MV. It can also be observed that the left-turn-out delays were generally higher than
left- turn-in delays. This can be explained by the fact that left-turn-out vehicles required a gap in both
the near-side and far-side traffic (i.e., traffic from both directions). Left-turn-in vehicles, however, only
needed gaps in traffic from one (mainline) direction.
50th Percentile Queue Length (ft) vs. Mainline Volume (vph)
The next two figures are graphs that show the 50th percentile queue lengths, again for LT-in volumes of
10 and 50 vph. Different threshold values of CC are also shown (since the difference in the queue
lengths were not much, the corner clearance “thresholds” are all shown on the same graph for
simplicity). Not surprisingly, it is observed that problems arise at higher mainline volumes. That is,
queue lengths become problematic (they block the driveway—graphically, the plotted queue lengths are
greater than the threshold values of CC) at higher values for MV and DV. The critical MV is estimated, in
these cases, to be about 1600vph with a DV of about 100vph or higher. It may be noted that for this
model, the average queue lengths were relatively shorter up to MV=1500vph due to the queues clearing
during the green phase of the signal.
0
50
100
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500
550
600
650
700
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Mainline Volume (veh/hr)
50%
Qu
eu
e L
en
gth
fo
r T
hro
ug
h M
ain
lin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=250ft
CC=350ft
CC=150ft
Figure 13. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=10vph
final report: page 43 of 67
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Mainline Volume (veh/hr)
50%
Qu
eu
e L
en
gth
fo
r T
hro
ug
h M
ain
lin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=150ft
CC=250ft
CC=350ft
Figure 14. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=50vph
Summary and Conclusions Based on Model 1 (Site 1)
The operational impacts of different values of (corner clearance) CC and driveway access types were
evaluated using Model 1 and varying MV (mainline volume), DV (driveway volume), and LT (left-turning
volume). (Reiterating, model 1 represents the case of a corner site before a signalized intersection,
where the lane configuration of the main road is one left-turn lane, two through lanes, and one right-
turn lane.) The figures (above) showing the various delays and 50% queue lengths for these different
values and under different turning scenarios were reviewed, and the results are summarized below. The
results are then used to derive “guidelines” for when left turns should be prohibited. The summary and
conclusions:
An increase in MV has relatively more impact on the average delay and queue length of the mainline traffic than increases in DV.
The negative impact due to increases in MV, DV, and LT was greater when CC was less than 150ft as opposed to 250ft or more.
When the MV approached 2000vph, the driveway was blocked for all values of CC and all combinations of DV and LT.
The impact of minimum and maximum DV on the average delay was more significant as MV approached 1500vph.
final report: page 44 of 67
In general, the average delay for RT-in/out+LT-in-only was greater as compared to a full-access driveway when MV reached 1500vph or higher. The possible reason for this higher delay for no left-turn-out is the assumption that the driveway trips are passer-by trips. Therefore, the left-turn-in traffic left the facility using the right-out exit and thus is added to the mainline traffic on the intersection approach being studied. However, for the full access case, this traffic is not added at the adjacent intersection; hence producing somewhat less average delay.
In general, all type of driveways performed similarly with respect to average delay when the MV was equal or less than 1500vph—i.e., the average total delay of the mainline traffic did not vary very much, regardless of the driveway type. However, RT-in/out+LT-in only and full access driveway types produced relatively larger delays due to the LT-in and out traffic.
The delay for LT-out traffic was more as compared to LT-in. The possible reason could be the extra time that LT-out vehicles have to experience in order to obtain gap in the near and far mainline traffic streams.
The queue lengths for mainline traffic became greater than the CC value(s) for about 50% of the time, when the MV approached 1300vph. The queues were greater when the LT volume was 50vph (vs. 10vph). It was observed that for a given value of CC, the driveway left turns became problematic for higher values of DV (closer to 150 and higher).
Recommended Access Control Guidelines Based on Model 1 (Site 1) Results
Based on the foregoing, the following access control guidelines are tentatively suggested for approach
geometry consisting of one left-turn-only lane, two through lanes, and one right-turn-only lane. These
will be fine-tuned and/or generalized as the results from other models are considered in subsequent
sections.
1) When the CC≤100ft and MV≥ 500vph, left turns in and out of the driveway should be prohibited. 2) When 100<CC≤150ft, MV≥1000vph, left turns out should be prohibited for left turn out traffic;
and in addition, the left turns in should be prohibited if DV≥150vph and LT≥10vph.
3) When 150<CC≤250ft, left turns in may be allowed as long as MV≤ 1500vph, DV≤ 150vph, and LT≤50vph. Left turns out may be allowed as long as MV≤ 1000vph, DV≤ 150vph, and LT≤50vph.
4) When 250<CC≤350ft, the criteria for allowing left turns in and out are the same as 3) above.
5) When CC>350ft, left turns in may be allowed as long as MV≤ 1500vph, DV≤ 150vph, and
LT≤50vph. Left turns out may be allowed as long as MV≤ 1500vph, DV≤150vph and LT≤50vph.
6) Caution should be exercised for allowing left turns for greater values of MV, as it would result in blocking the driveway by queues, even if CC approaches 450ft.
It should be noted that even though these are “recommendations,” they are not strict rules and could
be mitigated by unique conditions at a site. Before applying these recommendations, a site
final report: page 45 of 67
investigation including safety considerations should be done. These recommendations are summarized
in the chart on the following page. The chart is color-coded to show when left turns in and out of the
development should definitely be prohibited (red), when left turns in and out should be considered
separately or there are other issues to be considered (orange), and when they can be permitted (green).
In the next section, the second model (for a different geometric condition) is considered.
Results for Model 2 (lane configuration = 1 LT, 1 TH-only, 1 TH and RT—study sites 5 and 8)
Sites 5 and 8 are similar to site 1 except there is no exclusive RT lane. This site is also a typical arterial
roadway often found in suburban areas, a basic 5-lane section.
The observed split by turning movement is:
Left Through Right
8.0% 81.0% 11.0%
In this and succeeding sections, only narrative is presented although graphs similar to those for model
(site) 1 were also developed and analyzed—these are shown in appendix 6 but not explicitly referenced.
Summary and Conclusions Based on Model 2 (Sites 5 and 8)
Based on the combined results for average driveway-related delays and % queue lengths, the summary
and conclusions are:
Increase in MV has relatively more impact on the average delay and queue length of the mainline traffic than increases in DV.
The negative impact due to increase in MV, DV and LT was greater when CC < 150ft as opposed to 250ft or higher
The left-turn-out traffic was more negatively affected by increases in MV, DV, and LT than the left-turn-in traffic.
When the MV approached 2000vph, the driveway was blocked for all values of CC and all combinations of DV and LT.
final report: page 46 of 67
Fig
ure
x.
Su
mm
ary
of
Lef
t T
urn
Res
tric
tio
n R
eco
mm
end
ati
on
s fo
r M
od
el 1
Figu
re 1
5. S
um
mar
y o
f Le
ft T
urn
Res
tric
tio
n R
eco
mm
en
dat
ion
s fo
r M
od
el 1
RES
ULT
S FO
R L
EFT
TUR
N IN
/OU
T R
ESTR
ICTI
ON
REC
OM
MEN
DA
TIO
NS
MO
DEL
1Ty
pe
: Co
rner
Sit
e "B
efo
re"
Inte
rsec
tio
n
Nu
mb
er
of
Lan
es:
1 L
eft,
2 T
hro
ugh
, 1 R
igh
t
Pe
rce
nta
ge S
plit
of
Mai
nlin
e V
olu
me
at
the
Stu
dy
Leg:
Lef
t=9
.4%
, Th
rou
gh=7
7.6
%, R
igh
t=1
3.0
%
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
LEG
END
:C
C
= C
orn
er C
lear
ance
(ft
)N
OTE
S:
DV
= D
rive
way
Vo
lum
e (v
ph
) =>
En
teri
ng
fro
m t
he
Ad
jace
nt
Traf
fic
(fro
m N
ear-
Sid
e La
nes
)
MV
= M
ain
line
Vo
lum
e (v
ph
)
LT=
Left
Tu
rns
In a
nd
Ou
t (v
ph
) =>
No
t p
art
of
DV
=
Pro
hib
it L
T
=
May
Pro
hib
it L
T fo
r H
igh
er V
alu
es o
f D
V, L
T, M
V
=
May
Allo
w L
T
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" S
ho
uld
be
Pro
hib
ited
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e P
roh
ibit
ed f
or
Hig
her
Val
ues
of
DV
, LT,
MV
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e A
llow
ed
* C
C o
f 1
50
ft w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
CC
is <
= 1
00
ft, t
hen
LT
rest
rict
ion
s w
ill a
pp
ly e
ven
fo
r lo
wer
ran
ges
of
MV
.
**
CC
of
35
0ft
was
use
d in
th
e si
mu
lati
on
s. If
th
e C
C is
mu
ch h
igh
er t
han
35
0ft
, th
en L
T re
stri
ctio
ns
can
be
rela
xed
fo
r h
igh
er r
ange
s o
f M
V.
***
DV
of
15
0vp
h w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
DV
is m
uch
hig
her
than
15
0vp
h, t
hen
LT
rest
rict
ion
s w
ill b
eco
me
mo
re s
tric
t fo
r h
igh
er r
ange
s
of
MV
.
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
10
- 5
0<
10
Bas
ed o
n L
T D
elay
> 5
01
0 -
50
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
10
- 5
0
LT
> 5
01
0 -
50
< 1
0
LTLT
> 5
0
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
< 1
0
LTLT
LTLT
> 5
01
0 -
50
< 1
0
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
< 1
01
0 -
50
> 5
0
LT
LT
Bas
ed o
n L
T D
elay
CC
> 3
50
ft*
*
CC
= 2
50
- 3
50
ft
CC
= 1
50
- 2
50
ft
> 5
01
0 -
50
< 1
0
< 1
0
> 5
01
0 -
50
> 5
0
CC
< 1
50
ft*
DV
< 2
5D
V =
25
- 1
50
DV
> 1
50
***
< 1
01
0 -
50
> 5
0<
10
10
- 5
0>
50
< 1
0
LT
LTLT
> 5
01
0 -
50
< 1
0>
50
10
- 5
0<
10
final report: page 47 of 67
From the average delay graphs (similar to Model 1), the average delay for RT-in/out+LT-in-only (in general) was found out to be greater as compared to a full-access driveway when MV ≥ 1500vph.
In general, all types of driveways performed similarly with respect to average delay when the MV ≤ 1500vph—i.e., the average total delay of the mainline traffic was similar, regardless of the driveway type. However, RT-in/out+LT-in-only and full access driveway types produced relatively larger delays due to the LT-in and -out traffic.
For this model, it was observed that the queues dissipated much quicker even for higher volumes. The possible reason could be the fact that the traffic was relatively lower on the N-S approaches (i.e., the cross street at the intersection). This resulted in more green time for the E-W traffic (i.e., the study mainline traffic which is proportionally varied). So, even though, the 50th percentile queue lengths provided useful information, they were not used as a principal determinant to prohibit left turns.
Evolving Guidelines Based on Model 2 (Site 5 and 8)
Based on the foregoing, the evolving access guidelines are recommended for a development located at a
corner before a signalized intersection where the approach geometry is one left-turn, one through, and
one through-right (no exclusive right-turn lane) lanes:
1) When CC≤100ft and MV≥ 500vph, left turns in and out of the driveway should be prohibited. 2) When 100<CC≤150ft, both left turns in and out may be allowed as long as MV≤1000vph,
DV≤150vph, and LT≤10vph.
3) When 150<CC≤250ft, left turns in may be allowed as long as MV≤1000vph, DV~150vph (or up to 200vph), and LT≤10vph. Left turns out may be allowed as long as MV≤1000vph, DV≤150vph, and LT≤10vph.
4) When 250<CC≤350ft, left turns in may be allowed as long as MV≤ 1500vph, DV≤150vph, and
LT≤10vph. Left turns out may be allowed as long as MV≤1000vph, DV≤150vph, and LT≤50vph.
5) When CC>350ft, left turns in may be allowed as long as MV≤ 1500vph, DV≤150vph, and LT≤50vph. The left-turn-out criteria stay the same as in 4) above.
6) Similar to Model 1, caution should be exercised for allowing left turns for greater values of MV,
as it would result in blocking the driveway by queues, even if CC approaches 450ft.
These recommendations are summarized in the table on the next page.
final report: page 48 of 67
Figu
re 1
6. S
um
mar
y o
f Le
ft T
urn
Res
tric
tio
n R
eco
mm
en
dat
ion
s fo
r M
od
el 2
RES
ULT
S FO
R L
EFT
TUR
N IN
/OU
T R
ESTR
ICTI
ON
REC
OM
MEN
DA
TIO
NS
MO
DEL
2Ty
pe
: Co
rner
Sit
e "B
efo
re"
Inte
rsec
tio
n
Nu
mb
er
of
Lan
es:
1 L
eft,
2 S
har
ed T
hro
ugh
an
d R
igh
t
Pe
rce
nta
ge S
plit
of
Mai
nlin
e V
olu
me
at
the
Stu
dy
Leg:
Lef
t=8
.0%
, Th
rou
gh=8
1.0
%, R
igh
t=1
1.0
%
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
LEG
END
:C
C
= C
orn
er C
lear
ance
(ft
)N
OTE
S:
DV
= D
rive
way
Vo
lum
e (v
ph
) =>
En
teri
ng
fro
m t
he
Ad
jace
nt
Traf
fic
(fro
m N
ear-
Sid
e La
nes
)
MV
= M
ain
line
Vo
lum
e (v
ph
)
LT=
Left
Tu
rns
In a
nd
Ou
t (v
ph
) =>
No
t p
art
of
DV
=
Pro
hib
it L
T
=
May
Pro
hib
it L
T fo
r H
igh
er V
alu
es o
f D
V, L
T, M
V
=
May
Allo
w L
T
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" S
ho
uld
be
Pro
hib
ited
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e P
roh
ibit
ed f
or
Hig
her
Val
ues
of
DV
, LT,
MV
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e A
llow
ed
**
CC
of
35
0ft
was
use
d in
th
e si
mu
lati
on
s. If
th
e C
C is
mu
ch h
igh
er t
han
35
0ft
, th
en L
T re
stri
ctio
ns
can
be
rela
xed
fo
r h
igh
er r
ange
s o
f M
V.
***
DV
of
15
0vp
h w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
DV
is m
uch
hig
her
than
15
0vp
h, t
hen
LT
rest
rict
ion
s w
ill b
eco
me
mo
re s
tric
t fo
r h
igh
er r
ange
s
of
MV
.
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
LT
LTLT
10
- 5
0
LTLTLT
> 5
01
0 -
50
< 1
0
> 5
01
0 -
50
< 1
0
Bas
ed o
n L
T D
elay
DV
< 2
5
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
LTLT
> 5
01
0 -
50
< 1
0
< 1
0
> 5
01
0 -
50
> 5
01
0 -
50
< 1
0
< 1
0
> 5
0
DV
= 2
5 -
15
0D
V >
15
0**
*
< 1
01
0 -
50
> 5
0<
10
10
- 5
0>
50
< 1
0
Bas
ed o
n L
T D
elay
CC
> 3
50
ft*
*
CC
= 2
50
- 3
50
ft
CC
= 1
50
- 2
50
ft
CC
< 1
50
ft*
< 1
0
10
- 5
0
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
LTLT
< 1
0
> 5
0
Bas
ed o
n L
T D
elay
* C
C o
f 1
50
ft w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
CC
is <
= 1
00
ft, t
hen
LT
rest
rict
ion
s w
ill a
pp
ly e
ven
fo
r lo
wer
ran
ges
of
MV
.
LT
10
- 5
0
> 5
0
> 5
01
0 -
50
< 1
0
LT
> 5
01
0 -
50
final report: page 49 of 67
Results for Model 3 (lane configuration = 1 LT, 1 TH and RT lanes—study site 9)
Model 3, based on Site 9, is a basic 3-lane section with a center lane for left turns, but no exclusive right-
turn lane. It is a somewhat less typical arterial roadway type as compared to the sites for Models 1 and
2.
The observed split by turning movement is:
Left Through Right
2.5% 77.7% 19.8%
As was the case with the discussion of Model 2, the summary and conclusions and evolving
recommendations are presented here with the supporting figures showing explicit results provided in
appendix 7.
Summary and Conclusions Based on Model 3 (Site 9)
Based on the combined results for average driveway-related delays and analysis of queue lengths, the
summary and conclusions for this type of situation are:
Increase in MV has more impact on the average delay and queue length of the mainline traffic than increases in DV. This impact is more significant than for the two previous two situations. This is primarily due to the reduced capacity (less lanes) to accommodate higher mainline volumes.
The negative impact due to increase in MV, DV, and LT is greater when CC < 150ft as opposed to 250ft or higher.
The left-turn-out traffic was more negatively affected by increases in MV, DV, and LT as opposed to left-turn-in traffic.
When the MV approached 1000vph, the driveway was blocked for all values of CC and all combinations of DV and LT.
RT-in/out+LT-in only and full access driveway types produced relatively larger delays as compared to other driveway types due to LT in and out traffic.
Evolving Guidelines Based on Model 3 (Site 9)
Based on the summary and conclusions just presented and the details in the appendix, the following
guidelines are recommended for a development located at a corner before a signalized intersection
final report: page 50 of 67
where the approach geometry is one left-turn and one shared through-right lanes (no exclusive right-
turn lane) on the main road approach to the intersection:
1) When CC≤100ft and MV≥ 500vph, left turns in and out of the driveway should be prohibited. 2) When 100<CC≤150ft, left turns in and out may be allowed as long as MV≤ 500vph, DV≤150vph
(or approximately less than 200vph), and LT≤10vph.
3) When 150<CC≤250ft, left turns in may be allowed as long as MV<500vph, DV≤150vph (or slightly greater—up to approximately 200vph), and LT≤50vph. The criteria for the left turn out stay the same as in 2) above.
4) When 250<CC≤350ft, the criteria for both left turns in and out stay the same.
5) When CC>350ft, the criteria for left turns in and out stay the same, however, the criteria may be
relaxed for MV up to 700vph.
6) Caution must be exercised for allowing left turns for greater values of MV, as it would result in blocking the driveway by queues, even if CC approaches 450ft.
These recommendations are summarized in the following chart.
Results for Model 4 (lane configuration = 1 Shared LT- TH and 1 RT lanes—study site 7)
This site is not a typical arterial roadway configuration. It is sometimes found in low traffic suburban
areas, a basic 2-lane section which widens at the intersection to accommodate a right-turn lane. It
should be noted that since there is no median or center turn lane, vehicles wanting to turn left (in to the
site) do not have a storage space, as in earlier scenarios.
The observed split by turning movement is:
Left Through Right
18.8% 64.4% 18.8%
final report: page 51 of 67
Figu
re x
. Su
mm
ary
of
Left
Tu
rn R
estr
icti
on
Re
com
me
nd
atio
ns
for
Mo
de
l 3
RES
ULT
S FO
R L
EFT
TUR
N IN
/OU
T R
ESTR
ICTI
ON
REC
OM
MEN
DA
TIO
NS
MO
DEL
3Ty
pe
: Co
rner
Sit
e "B
efo
re"
Inte
rsec
tio
n
Nu
mb
er
of
Lan
es:
1 L
eft,
1 S
har
ed T
hro
ugh
an
d R
igh
t
Pe
rce
nta
ge S
plit
of
Mai
nlin
e V
olu
me
at
the
Stu
dy
Leg:
Lef
t=2
.5%
, Th
rou
gh=7
7.7
%, R
igh
t=1
9.8
%
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
LEG
END
:C
C
= C
orn
er C
lear
ance
(ft
)N
OTE
S:
DV
= D
rive
way
Vo
lum
e (v
ph
) =>
En
teri
ng
fro
m t
he
Ad
jace
nt
Traf
fic
(fro
m N
ear-
Sid
e La
nes
)
MV
= M
ain
line
Vo
lum
e (v
ph
)
LT=
Left
Tu
rns
In a
nd
Ou
t (v
ph
) =>
No
t p
art
of
DV
=
Pro
hib
it L
T
=
May
Pro
hib
it L
T fo
r H
igh
er V
alu
es o
f D
V, L
T, M
V
=
May
Allo
w L
T
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" S
ho
uld
be
Pro
hib
ited
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e P
roh
ibit
ed f
or
Hig
her
Val
ues
of
DV
, LT,
MV
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e A
llow
ed
**
CC
of
35
0ft
was
use
d in
th
e si
mu
lati
on
s. If
th
e C
C is
mu
ch h
igh
er t
han
35
0ft
, th
en L
T re
stri
ctio
ns
can
be
rela
xed
fo
r h
igh
er r
ange
s o
f M
V.
***
DV
of
15
0vp
h w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
DV
is m
uch
hig
her
than
15
0vp
h, t
hen
LT
rest
rict
ion
s w
ill b
eco
me
mo
re s
tric
t fo
r h
igh
er r
ange
s
of
MV
.
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
> 5
01
0 -
50
< 1
0
LT
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
10
- 5
0<
10
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
< 1
0
10
- 5
0<
10
* C
C o
f 1
50
ft w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
CC
is <
= 1
00
ft, t
hen
LT
rest
rict
ion
s w
ill a
pp
ly e
ven
fo
r lo
wer
ran
ges
of
MV
.
< 1
0
> 5
0
LT
> 5
01
0 -
50
< 1
0
10
- 5
0
> 5
01
0 -
50
CC
> 3
50
ft*
*
CC
= 2
50
- 3
50
ft
CC
= 1
50
- 2
50
ft
CC
< 1
50
ft*
DV
< 2
5D
V =
25
- 1
50
DV
> 1
50
***
< 1
01
0 -
50
> 5
0<
10
10
- 5
0>
50
< 1
0
LT
LTLTLT
> 5
01
0 -
50
< 1
0
> 5
01
0 -
50
> 5
01
0 -
50
LTLTLTLT
> 5
01
0 -
50
< 1
0>
50
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
< 1
0
> 5
0
LT
LT
final report: page 52 of 67
In the following paragraphs, a summary and conclusions based on the simulation results are
presented—detailed results are in appendix 8.
Summary and Conclusions Based on Model 4 (Site 7)
Based on the results for average driveway related delays and 50% queue lengths, the summary and
conclusions are:
Increase in MV has more impact on the average delay and queue length of the mainline traffic than increases in DV. This increase is greater than for Models 1 and 2, and closer to Model 3—this is due to the 2-lane section.
The negative impacts due to an increase in MV, DV, and LT were greater when CC < 150ft as opposed to 250ft or higher.
The left-turn-out traffic was more negatively affected by increases in MV, DV, and LT than was left- turn-in traffic.
When the MV approached 1000vph, the driveway was blocked for all values of CC and all combinations of DV and LT.
RT-in/out+LT-in only and full access driveway types produced relatively larger delays as compared to other driveway types due to LT in and out traffic.
Evolving Guidelines Based on Model 4 (Site 7)
Based on the foregoing, the following access guidelines are recommended for a development located at
a corner before a signalized intersection where the approach geometry is one left-turn/through lane and
and one right-turn lane (and summarized in the following chart):
1) When CC≤100ft and MV≥ 500vph, left turns in and out of the driveway should be prohibited. 2) When 100<CC≤150ft, left turns in may be allowed as long as MV≤ 500vph, DV≤150vph (or
approximately less than 200vph), and LT≤10vph. Left turns out may be allowed as long as MV≤ 500vph, DV≤150vph, and LT≤10vph.
3) When 150<CC≤250ft, the criteria for left turns in stay the same as above. The criteria for left
turns out also become the same as for left turns in.
4) When 250<CC≤350ft, the criteria stay the same as above
5) When CC>350ft, left turns in may be allowed as long as MV≤1000vph, DV≤200vph, and LT≤10vph. The criteria for left turns stay the same as previous.
6) Caution must be exercised for allowing left turns for greater values of MV, as it would result in
blocking the driveway by queues, even if CC approaches 450ft.
final report: page 53 of 67
Figu
re 1
8. S
um
mar
y o
f Le
ft T
urn
Res
tric
tio
n R
eco
mm
en
dat
ion
s fo
r M
od
el 4
RES
ULT
S FO
R L
EFT
TUR
N IN
/OU
T R
ESTR
ICTI
ON
REC
OM
MEN
DA
TIO
NS
MO
DEL
4Ty
pe
: Co
rner
Sit
e "B
efo
re"
Inte
rsec
tio
n
Nu
mb
er
of
Lan
es:
1 S
har
ed L
eft
and
Th
rou
gh, 1
Rig
ht
Pe
rce
nta
ge S
plit
of
Mai
nlin
e V
olu
me
at
the
Stu
dy
Leg:
Lef
t=1
8.8
%, T
hro
ugh
=62
.4%
, Rig
ht=
18
.8%
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
LEG
END
:C
C
= C
orn
er C
lear
ance
(ft
)N
OTE
S:
DV
= D
rive
way
Vo
lum
e (v
ph
) =>
En
teri
ng
fro
m t
he
Ad
jace
nt
Traf
fic
(fro
m N
ear-
Sid
e La
nes
)
MV
= M
ain
line
Vo
lum
e (v
ph
)
LT=
Left
Tu
rns
In a
nd
Ou
t (v
ph
) =>
No
t p
art
of
DV
=
Pro
hib
it L
T
=
May
Pro
hib
it L
T fo
r H
igh
er V
alu
es o
f D
V, L
T, M
V
=
May
Allo
w L
T
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" S
ho
uld
be
Pro
hib
ited
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e P
roh
ibit
ed f
or
Hig
her
Val
ues
of
DV
, LT,
MV
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e A
llow
ed
**
CC
of
35
0ft
was
use
d in
th
e si
mu
lati
on
s. If
th
e C
C is
mu
ch h
igh
er t
han
35
0ft
, th
en L
T re
stri
ctio
ns
can
be
rela
xed
fo
r h
igh
er r
ange
s o
f M
V.
***
DV
of
15
0vp
h w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
DV
is m
uch
hig
her
than
15
0vp
h, t
hen
LT
rest
rict
ion
s w
ill b
eco
me
mo
re s
tric
t fo
r h
igh
er r
ange
s
of
MV
.
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
LT
LTLT
10
- 5
0
LTLTLT
> 5
01
0 -
50
< 1
0
> 5
01
0 -
50
< 1
0
Bas
ed o
n L
T D
elay
DV
< 2
5
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
LTLT
> 5
01
0 -
50
< 1
0
< 1
0
> 5
01
0 -
50
> 5
01
0 -
50
< 1
0
< 1
0
> 5
0
DV
= 2
5 -
15
0D
V >
15
0**
*
< 1
01
0 -
50
> 5
0<
10
10
- 5
0>
50
< 1
0
Bas
ed o
n L
T D
elay
CC
> 3
50
ft*
*
CC
= 2
50
- 3
50
ft
CC
= 1
50
- 2
50
ft
CC
< 1
50
ft*
< 1
0
10
- 5
0
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
LTLT
< 1
0
> 5
0
Bas
ed o
n L
T D
elay
* C
C o
f 1
50
ft w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
CC
is <
= 1
00
ft, t
hen
LT
rest
rict
ion
s w
ill a
pp
ly e
ven
fo
r lo
wer
ran
ges
of
MV
.
LT
10
- 5
0
> 5
0
> 5
01
0 -
50
< 1
0
LT
> 5
01
0 -
50
final report: page 54 of 67
Results for Model 5 (lane configuration= (near side of adjacent road) 1 TH lane; (far side) 1 LT and 1
shared TH and 1 RT lanes —study site 3)
Model 5 (site 3) is similar to Model 3 (site 9) in the sense that the geometry of the lanes is similar.
However, this site is located AFTER the intersection rather than before it and, so, represents a departure
from the sites discussed thus far.
The observed split by turning movement (for traffic flowing to the left in the drawing above) at the
intersection is:
Left Through Right
4.1% 65.1% 30.8%
The observed split of traffic traveling left-to-right (a combination of traffic from the other three
approaches) is (assuming north direction upwards):
NB-R EB-TH SB-L
37.3% 60.0% 2.5%
In the following paragraphs, a summary and conclusions are presented as are recommendations for this
type of site. Detailed results (graphs) are presented in appendix 9.
Summary and Conclusions Based on Model 5 (Site 3)
Based on the combined results for average driveway-related delays and 50% queue lengths, the
conclusions are:
An increase in MV has more impact on the average delay and queue length of the mainline traffic than increases in DV. Although, the driveway is located “after” the intersection, and is not impacted by the blocking of queue lengths in the directly-adjacent mainline traffic, the delays obtained are very high due to the lack of lanes. The left-turn-out traffic has to wait for the queue (from the signal, going the opposite direction) to clear and thus adds to the left-turn-out delay. Similarly, left-turn-in delay is also impacted due to high volume on single through lane.
final report: page 55 of 67
The negative impact due to increases in DV and LT was greater when CC < 150ft as opposed to 250ft or higher.
The left turn out traffic was more negatively affected by increases in MV, DV and LT as opposed to left turn in traffic.
When MV approached 1000vph, the driveway was blocked for all values of CC and all combinations of DV and LT.
RT-in/out+LT-in only and full access driveway types produced relatively larger delays as compared to other driveway types due to LT in and out traffic.
Evolving Guidelines Based on Model 5 (Site 3)
Based on the foregoing, the following access guidelines are recommended for a development located at
a corner after a signalized intersection where the approach geometry on the near side is one through
lane, and the far side is one left-turn and one shared through and right lanes (no exclusive right-turn
lane):
1) When CC≤100ft and MV≥ 500vph, left turns in and out of the driveway should be prohibited. 2) When 100<CC≤150ft, left turns in may be allowed as long as MV<500vph, DV≥150-200vph, and
LT<50vph. Left turns out may be allowed as long as LT<10vph, with same conditions of MV and DV.
3) When 150<CC≤250ft, both left turns in and out may be allowed as long as long as MV<500vph,
DV≥150-200vph, and LT<50vph.
4) When 250<CC≤350ft, the criteria for left turns in and out are as above.
5) When CC>350ft, the criteria for both left turns in and out stay the same as above as long as the driveway stays within 450ft.
6) Caution must be exercised for allowing left turns for greater values of MV, as it would result in
blocking the driveway by queues, even if CC approaches 450ft. These recommendations are summarized in the following chart.
final report: page 56 of 67
Figu
re 1
9. S
um
mar
y o
f Le
ft T
urn
Res
tric
tio
n R
eco
mm
en
dat
ion
s fo
r M
od
el 5
RES
ULT
S FO
R L
EFT
TUR
N IN
/OU
T R
ESTR
ICTI
ON
REC
OM
MEN
DA
TIO
NS
MO
DEL
5Ty
pe
: Co
rner
Sit
e "A
fter
" In
ters
ecti
on
Nu
mb
er
of
Lan
es:
(N
ear
Sid
e) 1
Th
rou
gh, (
Far
Sid
e) 1
Lef
t, 1
Sh
ared
Th
rou
gh a
nd
Rig
ht
Pe
rce
nta
ge S
plit
of
Mai
nlin
e V
olu
me
at
the
Stu
dy
Leg:
Lef
t=4
.1%
, Th
rou
gh=6
5.1
%, R
igh
t=3
0.8
%
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
LEG
END
:C
C
= C
orn
er C
lear
ance
(ft
)N
OTE
S:
DV
= D
rive
way
Vo
lum
e (v
ph
) =>
En
teri
ng
fro
m t
he
Ad
jace
nt
Traf
fic
(fro
m N
ear-
Sid
e La
nes
)
MV
= M
ain
line
Vo
lum
e (v
ph
)
LT=
Left
Tu
rns
In a
nd
Ou
t (v
ph
) =>
No
t p
art
of
DV
=
Pro
hib
it L
T
=
May
Pro
hib
it L
T fo
r H
igh
er V
alu
es o
f D
V, L
T, M
V
=
May
Allo
w L
T
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" S
ho
uld
be
Pro
hib
ited
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e P
roh
ibit
ed f
or
Hig
her
Val
ues
of
DV
, LT,
MV
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e A
llow
ed
**
CC
of
35
0ft
was
use
d in
th
e si
mu
lati
on
s. If
th
e C
C is
mu
ch h
igh
er t
han
35
0ft
, th
en L
T re
stri
ctio
ns
can
be
rela
xed
fo
r h
igh
er r
ange
s o
f M
V.
***
DV
of
15
0vp
h w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
DV
is m
uch
hig
her
than
15
0vp
h, t
hen
LT
rest
rict
ion
s w
ill b
eco
me
mo
re s
tric
t fo
r h
igh
er r
ange
s
of
MV
.
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
> 5
01
0 -
50
< 1
0
LT
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
10
- 5
0<
10
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
< 1
0
10
- 5
0<
10
* C
C o
f 1
50
ft w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
CC
is <
= 1
00
ft, t
hen
LT
rest
rict
ion
s w
ill a
pp
ly e
ven
fo
r lo
wer
ran
ges
of
MV
.
< 1
0
> 5
0
LT
> 5
01
0 -
50
< 1
0
10
- 5
0
> 5
01
0 -
50
CC
> 3
50
ft*
*
CC
= 2
50
- 3
50
ft
CC
= 1
50
- 2
50
ft
CC
< 1
50
ft*
DV
< 2
5D
V =
25
- 1
50
DV
> 1
50
***
< 1
01
0 -
50
> 5
0<
10
10
- 5
0>
50
< 1
0
LT
LTLTLT
> 5
01
0 -
50
< 1
0
> 5
01
0 -
50
> 5
01
0 -
50
LTLTLTLT
> 5
01
0 -
50
< 1
0>
50
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
< 1
0
> 5
0
LT
LT
final report: page 57 of 67
Results for Model 6 (lane configuration= (near side of adjacent road) 2 TH lanes; (far side) 1 LT and 2 TH
and 1 RT lanes—study site 4)
Model 6 (site 4) is similar to Model 1 (site 1) in terms of the approach geometry of the intersection.
However, this site is located AFTER the intersection rather than before.
The observed split by turning movement (for traffic flowing to the left in the drawing above) at the
intersection is:
Left Through Right
22.8% 57.3% 19.9%
The observed split of traffic traveling left-to-right (a combination of traffic from the other three
approaches) is (assuming north direction upwards):
NB-R EB-TH SB-L
11.7% 69.0% 19.8%
In the following paragraphs, a summary and conclusions are presented as are recommendations for this
type of site. Detailed results (graphs) are presented in appendix 10.
Summary and Conclusions Based on Model 6 (Site 4)
Based on the combined results for average driveway-related delays and 50% queue lengths, the
conclusions are:
Similar to previous models, an increase in MV has more impact on the average delay and queue length of the mainline traffic than increases in DV.
The negative impact due to increases in DV and LT was greater when CC < 150ft as opposed to 250ft or higher.
The left-turn-out traffic was more negatively affected by increases in MV, DV, and LT than left-turn- in traffic.
final report: page 58 of 67
When MV approached 1500vph, the driveway was blocked for all values of CC and all combinations of DV and LT.
RT-in/out+LT-in only and full access driveway types produced relatively larger delays compared to other driveway types due to LT-in and -out traffic.
Evolving Guidelines Based on Model 6 (Site 4)
Based on the foregoing, the following access guidelines are recommended for a development located at
a corner after a signalized intersection where the approach geometry on the near side is two through
lanes, and the far side is one left-turn, two through, and one right-turn lanes:
1) When CC≤100ft and MV≥ 500vph, left turns in and out of the driveway should be prohibited. 2) When 100<CC≤150ft, left turns in may be allowed as long as MV<1000vph, DV≤150vph, and
LT<10vph. Left turns out may be allowed as long as MV≤ 500vph, DV~150-200vph, and LT<10vph.
3) When 150<CC≤250ft, the criteria for left turns stay the same. Left turns out may be allowed as
long as MV<1000vph, DV≤25vph, and LT<50vph. The criteria for left turns out stay the same.
4) When 250<CC≤350ft, left turns in may be allowed as long as MV<1000vph, DV≤150vph, and LT<50vph. Left turns out may be allowed as long as MV≤ 500vph, DV~150-200vph, and LT<50vph.
5) When CC>350ft, left turns in may be allowed as long as MV< 1000vph, DV~150-200vph, and LT<50vph as long as CC<450ft. The criteria for left turns out stay the same as above.
6) Caution must be exercised for allowing left turns for greater values of MV, as it may well result
in blocking the driveway by queues, even if CC approaches 450ft. These recommendations are summarized in the following chart.
Results for Model 7 (lane configuration (near side) = 2 TH, 1 LT, and 1 auxiliary lane (RT-in/out)—study
site 2)
This site is substantially different from those previously discussed insofar as this model is for a mid-block
scenario (not a corner site). The site is a typical arterial roadway type. It may be found in
urban/suburban commercial areas, a basic 5-lane section with an auxiliary right-turn in/out lane.
final report: page 59 of 67
Figu
re 2
0. S
um
mar
y o
f Le
ft T
urn
Res
tric
tio
n R
eco
mm
en
dat
ion
s fo
r M
od
el 6
RES
ULT
S FO
R L
EFT
TUR
N IN
/OU
T R
ESTR
ICTI
ON
REC
OM
MEN
DA
TIO
NS
MO
DEL
6Ty
pe
: Co
rner
Sit
e "A
fter
" In
ters
ecti
on
Nu
mb
er
of
Lan
es:
2 T
hro
ugh
Pe
rce
nta
ge S
plit
of
Mai
nlin
e V
olu
me
at
the
Stu
dy
Leg:
Lef
t=2
2.8
%, T
hro
ugh
=57
.3%
, Rig
ht=
19
.9%
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
LEG
END
:C
C
= C
orn
er C
lear
ance
(ft
)N
OTE
S:
DV
= D
rive
way
Vo
lum
e (v
ph
) =>
En
teri
ng
fro
m t
he
Ad
jace
nt
Traf
fic
(fro
m N
ear-
Sid
e La
nes
)
MV
= M
ain
line
Vo
lum
e (v
ph
)
LT=
Left
Tu
rns
In a
nd
Ou
t (v
ph
) =>
No
t p
art
of
DV
=
Pro
hib
it L
T
=
May
Pro
hib
it L
T fo
r H
igh
er V
alu
es o
f D
V, L
T, M
V
=
May
Allo
w L
T
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" S
ho
uld
be
Pro
hib
ited
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e P
roh
ibit
ed f
or
Hig
her
Val
ues
of
DV
, LT,
MV
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e A
llow
ed
Bas
ed o
n L
T D
elay
LT
> 5
01
0 -
50
< 1
0
LTLT
LT
> 5
01
0 -
50
< 1
0>
50
10
- 5
0<
10
Bas
ed o
n L
T D
elay
LTLT
> 5
01
0 -
50
< 1
0
> 5
0
Bas
ed o
n L
T D
elay
10
- 5
0>
50
< 1
0
< 1
0
> 5
01
0 -
50
< 1
0
> 5
01
0 -
50
Bas
ed o
n L
T D
elay
10
- 5
0
> 5
01
0 -
50
DV
< 2
5D
V =
25
- 1
50
DV
> 1
50
***
< 1
01
0 -
50
> 5
0<
10
Bas
ed o
n L
T D
elay
CC
> 3
50
ft*
*
CC
= 2
50
- 3
50
ft
CC
= 1
50
- 2
50
ft
CC
< 1
50
ft*
LTLTLT
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
* C
C o
f 1
50
ft w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
CC
is <
= 1
00
ft, t
hen
LT
rest
rict
ion
s w
ill a
pp
ly e
ven
fo
r lo
wer
ran
ges
of
MV
.
< 1
0
> 5
0
LT
> 5
01
0 -
50
< 1
0
Bas
ed o
n L
T D
elay
**
CC
of
35
0ft
was
use
d in
th
e si
mu
lati
on
s. If
th
e C
C is
mu
ch h
igh
er t
han
35
0ft
, th
en L
T re
stri
ctio
ns
can
be
rela
xed
fo
r h
igh
er r
ange
s o
f M
V.
***
DV
of
15
0vp
h w
as u
sed
in t
he
sim
ula
tio
ns.
If t
he
DV
is m
uch
hig
her
than
15
0vp
h, t
hen
LT
rest
rict
ion
s w
ill b
eco
me
mo
re s
tric
t fo
r h
igh
er r
ange
s
of
MV
.
LT
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
10
- 5
0<
10
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
LT
final report: page 60 of 67
Selected graphs and detailed results are provided in appendix 11.
Summary and Conclusions Based on Model 7 (Site 2)
In the case of a mid-block sites, the conclusion related to left-turn prohibition is primarily based on the
average delay related to left-turn-in and -out traffic. The maximum queue lengths within the driveway
show how long the queues become for a particular range of MV, DV, and LT, and can be problematic for
the development’s traffic operation. The comments that follow are based on the graphical results
shown in the appendix:
Increase in MV has more negative impact on the average delay for left-turn-in and -out traffic than increases in DV.
Left-turn-out traffic was more negatively affected by increases in MV, DV, and LT than left-turn-in traffic. This is due to the longer distance needed to be covered by the left-turn-out vehicles as opposed to left-turns-in. Left-turn-out vehicles waited relatively longer due to the requirement of a gap in both near-side and far-side mainline traffic.
When MV approached 1500vph, the left-turn-out traffic was practically jammed for all values of DV and LT. Left-turn-in traffic was able to enter the facility as long as it was low (<10vph).
Evolving Guidelines Based on Model 7 (Site 2)
Based on the foregoing, the following guidelines are recommended for a mid-block development where
the approach geometry on the near side is two through lanes, and one auxiliary lane for right-turn
in/out traffic:
1) When MV>1500vph, left turns in and out should be prohibited. 2) When 1000<MV≤1500vph, left turns out should be prohibited; however, if MV is less than
1200vph, left turns in may be allowed as long as LT <50vph and DV<150vph.
3) When 500<MV≤1000vph, left turns in can be allowed as long as DV≤200vph and LT≤50vph. Left turns out should be prohibited if DV≥150vph and LT≥50vph.
4) When MV<500vph, left turns in and out can be allowed as long as DV<150vph and LT≤50vph;
and, may be allowed for higher values of DV (i.e. up to approximately 200vph). In addition, left turns in may also be allowed if DV<150vph and LT>50 (up to approximately 100vph).
These recommendations are summarized in the following chart.
final report: page 61 of 67
Figu
re 2
1. S
um
mar
y o
f Le
ft T
urn
Res
tric
tio
n R
eco
mm
en
dat
ion
s fo
r M
od
el 7
RES
ULT
S FO
R L
EFT
TUR
N IN
/OU
T R
ESTR
ICTI
ON
REC
OM
MEN
DA
TIO
NS
MO
DEL
7Ty
pe
: Mid
-blo
ck S
ite
Nu
mb
er
of
Lan
es
(ne
ar s
ide
): 2
Th
rou
gh, 1
Au
xilia
ry (
RT
in/o
ut)
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
LEG
END
:C
C
= C
orn
er C
lear
ance
(ft
)N
OTE
S:
DV
= D
rive
way
Vo
lum
e (v
ph
) =>
En
teri
ng
fro
m t
he
Ad
jace
nt
Traf
fic
(fro
m N
ear-
Sid
e La
nes
)
MV
= M
ain
line
Vo
lum
e (v
ph
)
LT=
Left
Tu
rns
In a
nd
Ou
t (v
ph
) =>
No
t p
art
of
DV
=
Pro
hib
it L
T
=
May
Pro
hib
it L
T fo
r H
igh
er V
alu
es o
f D
V, L
T, M
V
=
May
Allo
w L
T
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" S
ho
uld
be
Pro
hib
ited
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e P
roh
ibit
ed f
or
Hig
her
Val
ues
of
DV
, LT,
MV
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e A
llow
ed
* D
V o
f 1
50
vph
was
use
d in
th
e si
mu
lati
on
s. If
th
e D
V is
mu
ch h
igh
er t
han
15
0vp
h, t
hen
LT
rest
rict
ion
s w
ill b
eco
me
mo
re s
tric
t fo
r h
igh
er r
ange
s o
f
MV
.
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
> 5
0>
50
< 1
0
LT
DV
< 2
5D
V =
25
- 1
50
DV
> 1
50
*
< 1
01
0 -
50
> 5
0<
10
10
- 5
0
LTLT
Bas
ed o
n L
T D
elay
10
- 5
0
final report: page 62 of 67
Results for Model 8 (lane configuration (near side) = 2 TH lanes—study site 6)
Site 6 is a stereotypical 5-lane suburban arterial. It differs from other models (except the immediately
preceding one) in that it is a mid-block site.
Detailed results are shown in appendix 12.
Summary and Conclusions Based on Model 8 (Site 6)
Following are the salient conclusions:
Similar to Model 7, increases in MV have more negative impact on the average delay for left turn-in and -out traffic than increases in DV.
The left-turn-out traffic was more negatively affected by increases in MV, DV, and LT than was left- turn-in traffic. The left-turn-out delay was relatively less as compared to Model 7. This can probably be attributed to the fact that the proportional mainline volume for the far side traffic was relatively less (-17.2%) for Model 8 than Model 7 (+64.3%)—this means that larger gaps were available for left-turn-out traffic for Model 8.
When the MV approached 2000vph, the left-turn-out traffic was practically jammed for all values of DV and LT, except when DV<25vph and LT<10vph. Left-turn-in traffic was able to enter the facility as long as it was less than 10vph.
Guidelines Based on Model 8 (Site 6)
Based on the foregoing, the following access guidelines are recommended for a mid-block development
where the approach geometry on the near side is two through lanes without any auxiliary lane for right-
turn in/out traffic:
1) When MV>2000vph, left turns in and out should be prohibited. 2) When 1500<MV≤2000vph, left turns out should be prohibited. Left turns in may be allowed as
long as MV<1700vph, DV<200vph, and LT<10vph.
3) When 1000<MV≤1500vph, left turns out should be prohibited if DV>25vph and LT>10vph. Left turns in may be allowed as long as LT<10vph and DV<150.
4) When 500<MV≤1000vph, left turns out should be prohibited if DV≥150vph and LT≥50vph; and,
may be allowed if DV<25vph and LT<50vph. Left turns in can be allowed as long as DV<200vph and LT<50vph.
final report: page 63 of 67
5) When MV<500vph, left turns in and out can be allowed as long as DV<150vph and LT≤50vph;
and, may be allowed for higher values of DV (i.e. up to approximately 200vph). In addition, left turns in may also be allowed if DV<150vph and LT>50 (up to approximately 100vph).
These recommendations are summarized in the following chart.
OVERARCHING RESULTS AND RECOMMENDATIONS
Based on the results from the safety and operational analyses, overall results and recommendations can
be presented. First, the results from the operational modeling of different roadway configurations were
reviewed which showed certain similarities. These are presented below, followed by the general access
guidelines (broken down by corner and mid-block sites).
SUMMARY OF RESULTS FROM OPERATIONAL MODELING OF DIFFERENT ROADWAY CONFIGURATIONS
An increase in MV has relatively more impact on the average delay and queue length for the mainline traffic than an increase in DV.
The negative impact due to increases in MV, DV, and LT was greater when CC was less than 150ft as opposed to 250ft or more.
When the MV approached 2000vph, the driveway was typically blocked for all values of CC and all combinations of DV and LT.
The impact of minimum and maximum DV on the average delay was greater as MV approached 1500vph.
The delay for LT-out traffic was typically greater than delay for LT-in traffic.
For corner sites, the 50th percentile queue length blocked the driveway when the mainline volume reached more than 1500vph. The maximum CC used was 350ft.
GENERAL ACCESS GUIDELINES BASED ON OPERATIONAL MODELING
Corner Sites For corner sites on a basic 5-lane section adjacent to the development (for sites both “before” and
“after” the intersection), the following are the guidelines:
1) When CC≤100ft and MV≥500vph, left turns in and out of the driveway should be prohibited for
any volume of DV and LT.
final report: page 64 of 67
Figu
re 2
2. S
um
mar
y o
f Le
ft T
urn
Res
tric
tio
n R
eco
mm
en
dat
ion
s fo
r M
od
el 8
RES
ULT
S FO
R L
EFT
TUR
N IN
/OU
T R
ESTR
ICTI
ON
REC
OM
MEN
DA
TIO
NS
MO
DEL
8Ty
pe
: Mid
-blo
ck S
ite
Nu
mb
er
of
Lan
es
(ne
ar s
ide
): 2
Th
rou
gh
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
InO
ut
> 2
00
0
> 2
00
0
> 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
15
00
- 2
00
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
MV
10
00
- 1
50
0
50
0 -
10
00
50
0 -
10
00
50
0 -
10
00
< 5
00
`<
50
0
< 5
00
LEG
END
:C
C
= C
orn
er C
lear
ance
(ft
)N
OTE
S:
DV
= D
rive
way
Vo
lum
e (v
ph
) =>
En
teri
ng
fro
m t
he
Ad
jace
nt
Traf
fic
(fro
m N
ear-
Sid
e La
nes
)
MV
= M
ain
line
Vo
lum
e (v
ph
)
LT=
Left
Tu
rns
In a
nd
Ou
t (v
ph
) =>
No
t p
art
of
DV
=
Pro
hib
it L
T
=
May
Pro
hib
it L
T fo
r H
igh
er V
alu
es o
f D
V, L
T, M
V
=
May
Allo
w L
T
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" S
ho
uld
be
Pro
hib
ited
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e P
roh
ibit
ed f
or
Hig
her
Val
ues
of
DV
, LT,
MV
= Le
ft T
urn
s In
/Ou
t as
a "
Pai
r" M
ayb
e A
llow
ed
DV
< 2
5D
V =
25
- 1
50
DV
> 1
50
*
< 1
01
0 -
50
> 5
0
LTLT
Bas
ed o
n L
T D
elay
10
- 5
0<
10
10
- 5
0
* D
V o
f 1
50
vph
was
use
d in
th
e si
mu
lati
on
s. If
th
e D
V is
mu
ch h
igh
er t
han
15
0vp
h, t
hen
LT
rest
rict
ion
s w
ill b
eco
me
mo
re s
tric
t fo
r h
igh
er r
ange
s o
f
MV
.
Bas
ed o
n L
T D
elay
Bas
ed o
n L
T D
elay
> 5
0>
50
< 1
0
LT
final report: page 65 of 67
2) When MV≥1500vph, left turns in and out should be prohibited for any combination of CC, DV,
and LT.
3) When 1000>MV≥1500vph, left turns in and out should be prohibited if DV>150vph and LT>50vph for any CC.
4) When 500>MV≥1000vph and LT≥50vph, an extra care should be taken before allowing left turns in and out. For MV closer to 1000vph, the left turn prohibition criteria would become more important.
5) Caution must be exercised in allowing left turns for greater values of MV, as it would result in blocking the driveway by queues, even if CC approaches 450ft.
For other corner sites (i.e., on basic 3-lane or 2-lane [no TWLTL] sections),the following guidelines are
recommended regardless of whether the site is “before” or “after” the intersection:
1) When CC≤100ft, left turns in and out of the driveway should be prohibited for any combination
of CC, DV, and LT.
2) When MV≥1000vph, left turns in and out should be prohibited for any combination of CC, DV, and LT.
3) When 500>MV≥1000vph, left turns in and out should be prohibited if DV>150vph and LT>10vph for any CC.
4) Similarly, caution must be exercised in allowing left turns for greater values of MV, as it would result in blocking the driveway by queues, even if CC approaches 450ft.
Mid-Block Sites
1) When MV≥1500vph, left turns in and out are recommended to be prohibited for any combination of DV and LT.
2) When 1000>MV≥1500vph, left turns in and out should be prohibited if DV>150vph and LT>50vph. For lower volumes of DV and LT, restrictions would be more important as MV approaches 1500vph.
3) When MV≤1000vph, LT<10vph (may go up to 20vph) and DV<25vph (may go up to 50vph), left
turns in and out can be allowed.
4) Even if MV<1000vph, caution must be exercised for allowing left turns, especially for higher values of DV and LT.
final report: page 66 of 67
OVERARCHING SAFETY CONSIDERATIONS
Compared to the operational concerns, safety considerations were viewed as being less significant since
the crash reductions that might be expected from access restrictions appeared to be relatively modest.
This observation is consistent with earlier research. Moreover, crash reductions appear to be relevant
only in situations where the ADT is relatively high—greater than 15,000 vpd (which roughly corresponds
to a peak hour volume of 1200-1800 vph). Thus, the most problematic volumes for operational
concerns roughly coincide with those for safety. That is, overlaying safety concerns with operational
issues does not significantly change any of the guidelines. That being said, it was clear from the safety-
related review that there is considerable variation in crash history by site. So, crash histories should
always be reviewed when specific sites are being reviewed/evaluated for implementation of access
control measures.
DISCUSSION
In general, the driveways are designated as either full access or right-in-right-out, the main focus of the
project was to observe and determine under what conditions left turns in and out of the facility become
problematic and must be restrained. Right-turn (in or out) driveway traffic is generally not critical from
either the operation or safety perspectives as opposed to left-turn traffic due to fewer conflict points.
The consideration of right-turn-out delays was not highlighted due to similar results for almost all the
models. It was observed that for sites with a basic 5-lane section (including mid-block sites), the right-
out delays were higher than the acceptable LOS when the CC<150ft, MV>1000vph, DV>150vph, and
MV>50vph. For CC ≥250, the MV could be up to 1500vph. Similarly, for basic 2- and 3-lane sections, the
right-out delay was beyond the acceptable limits when CC<150ft, MV>500vph, DV>150vph, and
MV>1000vph.
When applying any of these guidelines, it should be remembered that all of the operations modeling
was done using hourly volumes. These ranged from very low numbers to near-capacity conditions.
Most importantly, the operational problems typically arose at the higher end of that range. What this
means is that the problems noted are generally occurring during peak or otherwise high volume
hours/situations—at other times of the day, the problems (e.g., delays and queues) would be much less
apparent. Put another way, there may well be only a couple of times in a day when access restrictions
are really necessary.
final report: page 67 of 67
One aspect of access control that was not covered in this project was the actual design of the access
control (e.g., required shape and size of channelizing island). During the observations done at the nine
sites, turning violations were often noted—i.e., even though left turns in and/or out were prohibited,
many drivers made (or attempted to make) the turn anyway. This was, for example, routinely observed
at the MSUFCU on Saginaw (site 2) where drivers went around and even over the small raised island that
was meant to prohibit turns. The point of mentioning that here is that whenever turns are restricted,
significant islands and signs must be used if drivers are really going to be expected to not make the
prohibited turn(s).
It should be noted that the guidelines developed and presented here should be carefully applied, based
on proper geometrical, volume, and signal data gathered in the field. Any specific site may present
some factors (or local conditions) which need to be studied “on-site” to come up with conclusions
regarding restricting or allowing left turns related to the development. Different sites may have similar
geometric configurations as the study sites selected for this project; however, they might have different
volume percentage splits at the intersection, speed limit, signal phases, driveways of adjacent/nearby
developments, and other landscape/visual obstructions-related factors. Therefore, it is highly
recommended to investigate each site individually before applying these guidelines.
references—page 1
REFERENCES General References Driveway and Street Intersection Spacing. Transportation Research Circular, 456. Transportation Research Board, 1996. Impacts of Access Management Techniques. National Cooperative Highway Research Program, Report 420. Transportation Research Board, 1999.
Lu, J and Dissanayake, S and Xu, L and Williams, K. Safety Evaluation of Right Turns Followed by U-Turns as an Alternative to Direct Left Turns - Crash Data Analysis. University of South Florida, Tampa; Florida Department of Transportation, 2001.
Dorothy, P W and Maleck, T L and Nolf, S E. Operational Aspects of Michigan Design for Divided Highways. Transportation Research Board, 1997.
Gluck, J S and Haas, G and Mahmood, J and Levinson, H S. Driveway Spacing and Traffic Operations. Transportation Research Board, 2000.
Thieken, Stephen L and Croft, Frank M. An Evaluation of Characteristics That Impact Violation Rates at Right-in/Right-out Driveways. Federal Highway Administration, 2004.
Chowdhury, Mashrur A and Derov, Nichole and Tan, Paulin. Evaluating the Effects of Prohibiting Left Turns and the Resulting U-Turn Movement. University of Dayton; Ohio Department of Transportation; Federal Highway Administration, 2003.
Dissanayake, S and Lu, J. Access Management Techniques to Improve Traffic Operations and Safety: A Case Study of a Full Vs. Directional Median Opening. Center for Transportation Research and Education, 2003.
Chowdury, M and Derov, N and Tan, P and Sadek, A. Prohibiting Left-Turn Movements at Mid-Block Unsignalized Driveways: Simulation Analysis. American Society of Civil Engineers, 2005. Access Management Manual. Transportation Research Board, National Academy Press, Washington, D.C., 2003. Box, P C. EFFECT OF INTERSECTIONS ON DRIVEWAY ACCIDENTS. Federal Highway Administration, 2000. Castillo, nelson. Should Direct Left Turns from Driveway be Avoided? A Safety Perspective. Institute of Transportation Engineers, ITE Journal, 2002.
Chowdhury, M. A., Derov, N., Tan, P., and Stemen, C. A Survey of State Practices for Restricting Direct Left Turns from Driveways. Institute of Transportation Engineers, 2004.
Federal Highway Administration, Technical Guidelines for the Control of Direct Access to Arterial Highways, Volume II, Report No. FHWA-RD-76-87, Washington, DC, 1975.
references—page 2
Federal Highway Administration, Signalized Intersections: Informational Guide, Report No.FHWA-HRT-04-091, August 2004 National Highway Institute (NHI), Access Management, Location and Design: Participant Notebook, NHI Course No. 15255, U.S. Department of Transportation, Federal Highway Administration, Washington, DC, 1992. Rawlings, Jonathan and Gattis, J L. Detailed Study of Driveway Collision Patterns in an Urban Area. Transportation Research Board, 2008. State Documents Transportation, C. D. o. (1998, March 2002). "State Highway Access Code " Retrieved Jan 3, 2008, from http://www.dot.state.co.us/AccessPermits/PDF/601_1_AccessCode_March2002_.pdf. Transportation, D. D. o. (2002, Oct 29, 2007). "Standards and Regulations for Access to State Highways." Retrieved Jan 3, 2008, from http://www.deldot.gov/information/pubs_forms/manuals/entrance_manual/index.shtml. Gary Sokolow, J. S., Vergil Stover, Frank Broen, Amy Datz, Laura A. Borgesi. (March 2005). "Driveway Handbook." Retrieved Jan 4, 2008, from http://www.dot.state.fl.us/planning/systems/sm/accman/. Transportation, G. D. o. (March 2004). "Regulations for Driveway and Encroachment Control." Retrieved Jan 4, 2008, from http://www.dot.state.ga.us/doingbusiness/PoliciesManuals/roads/Documents/DesignPolicies/DrivewayFull.pdf. Transportation, I. D. o. (1996). "Driveway Permit Manual." Retrieved Jan 5, 2008, from http://www.in.gov/indot/files/drivewaymanual-permits.pdf. Transportation, I. D. o. (December 2005). "Iowa Primary Road Access Management Policy." Retrieved Jan 5, 2008, from http://www.iowadot.gov/operationsresearch/reports.aspx. Transportation, k. D. o. (2003). "Corridor Management Policy." Retrieved Jan 5, 2008, from http://www.ksdot.org/BurTrafficEng/cmpworking/cmpindex.asp. Cabinet, C. o. K. T. (Jan 2006). "Highway Design Guidance Manual." Retrieved Jan 5, 2008, from http://transportation.ky.gov/design/designmanual. Transportation, M. D. o. (2005, Mar 1, 2007). "Maine DOT Access Management Publications." Retrieved Jan 6, 2008, from http://www.maine.gov/mdot/planning-process-programs/access-mngmnt.php. Administration, S. H. (Jan 2004). "State Highway Access Manual." Retrieved Jan 6, 2008, from http://www.marylandroads.com/businesswithsha/bizStdsSpecs.asp?id=B157+B159 Mark A. Wyckoff, F. a. M. M., AICP, Planning and Zoning Center, Inc. (2001). "The Access Management Guidebook." Retrieved Jan 6, 2008, from http://www.michigan.gov/mdot/0,1607,7-151-
references—page 3
9622_11044_11367---,00.html. Transportation, M. D. o. (March 2002, Jan 2, 2008). "Mn/DOT Access Management Manual." Retrieved Jan 6, 2008, from http://www.dot.state.mn.us/d6/projects/TH61/TH_61_Corridor_Managment_Plan/Appendices/Appendix_I.pdf. Roads, N. D. o. (March 2006, Oct 30, 2006). "Access Control Policy to the State Highway System." Retrieved Jan 7, 2008, from http://www.dor.state.ne.us/roway/pdfs/accesscontrol.pdf. Transportation, N. D. o. (July 1999, Dec 3, 2007). "Access Management System and Standards." Retrieved Jan 7, 2008, from http://www.nevadadot.com/business/forms/pdfs/TrafEng_AccesMgtSysStandards.pdf. Transportation, N. J. D. o. (2007, Jul 31, 2008). "State Highway Access Management Code." Retrieved Jan 9, 2008, from http://www.state.nj.us/transportation/about/rules/pdf/chapter47.pdf. Department, N. M. S. H. a. T. (2001). "State Access Management Manual." Retrieved Jan 11, 2008, from http://nmshtd.state.nm.us/main.asp?secid=11703. Transportation, N. C. D. o. (July 2003, Aug 22, 2003). "Policy on Street and Driveway Access to North Carolina Highways." Retrieved Jan 12, 2008, from http://www.ncdot.org/doh/preconstruct/altern//value/manuals/pos.pdf. Transportation, N. Y. S. D. o. (November 2003, Jan 27, 2004). "Policy and Standards for the Design of Entrances to State Highways." Retrieved Jan 11, 2008, from https://www.nysdot.gov/regional-offices/region4/Repository/residentialdriveways.pdf. Transportation, O. D. o. (Dec 2001, Mar 24, 2008). "State Highway Access Management Manual." Retrieved Jan 12, 2008, from http://www.dot.state.oh.us/Divisions/ProdMgt/Roadway/AccessManagement/Documents/State Highway Access Management Manual March 2008.pdf Transportation, O. D. o. (2000, April 23, 2008). "Access Management Manual." Retrieved Jan 12, 2008, from http://www.oregon.gov/ODOT/HWY/ACCESSMGT/accessmanagementmanual.shtml. Transportation, P. D. o. T. a. T. U. S. D. o. (April 2005, Feb 2006). "Access Management Model Ordinances for Pennsylvania Municipalities Handbook." Retrieved Jan 13, 2008, from ftp://ftp.dot.state.pa.us/public/PubsForms/Publications/PUB%20574.pdf. Transportation, R. I. D. o. (Feb 2005). "Rules and Regulations Concerning Permission for Use of State Highway Rights-of-Way." Retrieved Jan 13, 2008, from http://www.dot.state.ri.us/publications/index.asp. Transportation, S. C. D. o. (2008, Aug 18, 2008). "Access and Roadside Management Standards." 2008 Edition. Retrieved Jan 15, 2008, from http://www.scdot.org/doing/trafficengineering.shtml#accessRoadside. Transportation, S. D. D. o. (1999, Dec 22, 2006). "Road Design Manual." Retrieved Jan 13, 2008, from
references—page 4
http://www.sddot.com/pe/roaddesign/plans_rdmanual.asp. Transportation, T. D. o. (2004, June 2004). "Access Management Manual." Retrieved Jan 15, 2008, from http://onlinemanuals.txdot.gov/txdotmanuals/acm/index.htm. Transportation, U. D. o. (May 2007, Oct 9, 2008). "Roadway Design Manual of Instruction." Retrieved Jan 15, 2008, from http://www.dot.state.ut.us/main/f?p=100:pg:2992327358946411::::T,V:1498,. Transportation, V. A. o. (1999, July 22, 2005). "Access Management Program Guidelines." Retrieved Jan 15, 2008, from http://www.aot.state.vt.us/business.htm. Transportation, V. D. o. (2007, July 2007). "Road Design Manual." Retrieved Jan 16, 2008, from http://www.virginiadot.org/business/locdes/rdmanual-index.asp. Transportation, W. S. D. o. (Jan 2006, May 2008). "Design Manual." Retrieved Jan 16, 2008, from http://www.wsdot.wa.gov/Design/Policy/default.htm. Transportation, W. V. D. o. (May 2004, Sep 21, 2005). "Manual on Rules and Regulations for Constructing Driveways on State Highway Rights-of-Way." Retrieved Jan 17, 2008, from http://www.wvdot.com/engineering/Manuals/Traffic/Driveway.pdf. Transportation, W. D. o. (2005, Jul 19, 2005). "WYDOT Access Manual." Retrieved Jan 17, 2008, from http://dot.state.wy.us/Default.jsp?sCode=infwa.
Appendix 1. Summary of Turn-Restriction Practices
Appendix 1. Summary of Turn Restriction Policies
Documentation Full Access Width Criteria
RT-in/out LT-in/out Vehicular Volume/Type of Driveway Min (ft) Max (ft) Access Class
Median Type or
Speed (mph) or
Control
Min Distance(ft)
Design Condition Throat width Speed Spacing (feet)(1) Speed IMCC
20 120 30 325
25 190 35 425
30 320 40 525
35 450 45 630
40 620 50 750
45 860 55 875
50 1,125 60 1005
55 1,500
60 1,875
Access Management Manual 2003
SUVV* ≤5 DHV** 16 30 25 150
SUVV>5 DHV or if multi-unit vehicles present 25 40 30 200
35 250
40 325
* Single Unit Vehicular Volume 45 400
** Design Hourly Volume 50 475
55 550
60 650
65 725
70 850
50
Trips/Day(at driveway) Trips/HourMedian Treatment and
Access RoadsPosition Access Allowed
1-20 1-5 12 24
21-600 6-60 24 36 2
Restrictive with Service
Roads *1320/660 Approaching Intersection Right In/Out 115
601-4000 61-400 24 36 3 Restrictive 660/440 Approaching Intersection Right In Only 75
4 Non-Restrictive 660/440 Departing Intersection Right In/Out 230(125)*
Departing Intersection Right Out Only 100
5 Restrictive 440/245
6 Non-Restrictive 440/245 Approaching Intersection Full Access 230(125)*
7 Both Median Types 125 Approaching Intersection Right In Only** 100
* >45 mph / ≤45 mph Departing Intersection Full Access 230(125)*
Departing Intersection Right Out Only** 100
30
Full access is
allowed with
appropriate median
crossover spacing,
auxiliary lanes on the
highway, adequate
channelization and
dedicated lanes for
all movements.
20
Corner clearance has been taken from the document "Access
management standarsds-Rule 14-97"
Without Restrictive Median
For residential access within subdivision streets 12
Not addressed
specifically, but can
be derived from the
turning restrictions.
Combined residential entrance serving two
residential properties24
Driveway Handbook
March 2005
DelDOT Manual
When private access is
permitted, left turns may
be allowed if in the opinion
of the department such
left turns can be
reasonably accomplished
and it is not a divided
highway. (See details in
description)
Not available online
Width of Driveway
Driveway Width Corner Clearance at IntersectionDriveway Spacing
(Distance of Driveway from the Intersection)
Left turns exiting the
driveway are permitted but
for that, separate left turn
lane is to be provided in
the driveway.
Not available online
Not addressed
specifically, but can
be derived from the
turning restrictions.
California
Not available online
Not available online
Not available online
ColoradoState Highway Access
Code March 2002
State
Rules for Driveway movements
Restrictive Access
Left turns are allowed
where design meets all
safety requirements
[undefined]. Median cross-
over and channelization is
provided to account for
both right and left turns.
Storage lanes should be
provided by checking the
volume warrants for left-
turn lane.
Channelized driveway
islands may be required
for turn restricted
driveways when the
driveway volume is
predicted to exceed 100
DHV, no restrictive center
median is in place or
programmed to be
constructed or it is likely
that there will be frequent
violations of the turn
restrictions.
Delaware
Florida
Alabama
Alaska
Arizona
Arkansas
Connecticut
Criteria
Category 4: Local
(minor collectors or local
roads)
Min Driveway Spacing(ft)
Spacing Criteria
L=N/28*20
where L = back of shoulder at intersection to
center line of enterance; N = No of vehicles
expected to approach the intersection in design
hour.Category 3: Collectors
(minor arterial or major
collector)
250
With Restrictive Median
Spacings given are for residential access only
Generally Developed
Generally Developing or UndevelopedWhere minimum corner
clearance cannot be met,
due to specific site
conditions,you should at
least try and get 125 to
230ft of corner clearance.
In these cases it is most
important to prohibit(or
limit) left turns from these
driveway locations.Right
turn in/out only driveway is
provided with "pork-chop
channelization" and with
appropriate signs like "Do
Not Enter" or "Right Lane
Must Turn Right" or with
flexible posts on main road
to discourage left turns.
200
Category 2: Principle
arterials400
Right-turn in/out only
driveways are controlled
with proper channelization
and pavement markings.
Not available online
NCHRP Report 420 (1999)
IMCC=Initial minimum corner clearance
distances for under saturated conditions.
Corner clearance for different traffic conditions
can be adjusted by multiplying IMCC with
adjustment factors.
(1) 1.5 times the distance required for a passenger car on level
terrain to accelerate from zero to through traffic speed based
on acceleration information from NCHRP Report 270 as
contained in the 1990 AASHTO Green Book
Transportation Research Circular No 456,March 1996
NCHRP reports
25AASHTO advises that
driveways not to be
permitted within the
functional area of an
intersection, therefore
there should be sufficient
corner clearance to
separate access
connections from roadway
intersections.Where no
alternatives exist, common
practice is for the
permitting department to
allow construction of an
access connection along
the property line farthest
from the intersection.In
such cases, agencies
typically reserve the right
to require directional
connections (i.e., right-
in/out, right in only, or right
out only) or to require
nonconforming corner
properties to share access
with abutting properties. (Access Management
Manual 2003)
No information was found
when left turns are
allowed,but can be
derived from the
information given in RT-
in/out column.
Not addressed
specifically, but can
be derived from the
turning restrictions.Simultaneous entry and exit by single-unit trucks 40
All above mentioned widths are for driveways with no bike
lane
Single-lane exit, entering passenger car must wait
until an exiting vehicle clears the driveway
Simultaneous exit by passenger car and entry by
single-unit truck40
Separate left-turn and right-turn exit lanes for
passenger cars and simultaneous entry by
passenger car
43
Simultaneous entry and exit by passenger cars 35
Driveway width standards are same both for rural section
(flush shoulder) and urban section (curb & gutter)
For * and **, refer to description
Appendix 1. Summary of Turn Restriction Policies
Documentation Full Access Width Criteria
RT-in/out LT-in/out Vehicular Volume/Type of Driveway Min (ft) Max (ft) Access Class
Median Type or
Speed (mph) or
Control
Min Distance(ft)
Width of Driveway
Driveway Width Corner Clearance at IntersectionDriveway Spacing
(Distance of Driveway from the Intersection)
State
Rules for Driveway movements
Restrictive Access
Criteria
Min Driveway Spacing(ft)
Spacing Criteria
NCHRP reports
AASHTO advises that
driveways not to be
permitted within the
functional area of an
intersection, therefore
there should be sufficient
corner clearance to
separate access
connections from roadway
intersections.Where no
alternatives exist, common
practice is for the
permitting department to
allow construction of an
access connection along
the property line farthest
from the intersection.In
such cases, agencies
typically reserve the right
to require directional
connections (i.e., right-
in/out, right in only, or right
out only) or to require
nonconforming corner
properties to share access
with abutting properties. (Access Management
Manual 2003)
No information was found
when left turns are
allowed,but can be
derived from the
information given in RT-
in/out column.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Current Residential GA Std. 14 18 25 125
Current Commercial (One Way) GA Std 16 20 30 125
Current Commercial (Two Way) GA Std 24 40 35 150
40 185
45 230
50 275
55 350
60 450
65 550
1-way access 16 24 30 185
35 245
40 300
45 350
50 395
55 435
Residential driveway 10 28 Local street 150 Local streets 30
Commercial and multifamily driveway 24 36 Collector 185 Collector streets 75
Minor arterial 230 Minor arterial 100
Major arterial 275 Major arterial 120
Low Vol(Type1& 2) 12 30 1,2,3, & 4 Developed 205
Commercial Type 4, 5 &6 24 36 5 & 6 Developed 340
Industrial Type 5& 6 24 40 1,2,3,& 4 Undeveloped 2640
Joint use Type 1,2 ,4,5 & 6 [2] [2] 5 & 6 Undeveloped 430
Low Vol(Type1& 2) 12 24
Commercial Type 4, 5 &6 12 24
Industrial Type 5& 6 *[1]20 *[1]40
Joint use Type 1,2 ,4,5 & 6 *[2] *[2]
Trips/Day Trips/Hour
1-20 1-5 12 24 1 Restrictive 1200/600
21-600 6-60 24 36 2 Restrictive Preffered 600/400
601-4000 61-400 24 36 3 Non-Restrictive 400/300
4 Non-Restrictive 150*/125
Posted Speed (mph)
25 or less Not Applicable
Driveway onto a Mobility Arterial 12 22 30 Not Applicable
35 Not Applicable
40 175
45 265
50 350
55 or more 525
A waiver is required for special case
24
Not addressed
specifically, but can
be derived from the
turning restrictions.
For 2-way access,if any of the following apply;(a)
Vehicle volume exceeds 5DHV(b) Multi-unit vehicles
will use the access(c) Single-unit vehicles of more
than 30' in length will use the access(d)Vehicles of
more than 16' in width will use the access.
25
20
Driveway onto any highway locate outside urban
compact areas12
Full access is
allowed with GDOT
detailed Design for
Median Crossovers
on Divided State
Highways.
Not addressed
specifically, but can
be derived from the
turning restrictions.
2-way accesses if the single-unit vehicle
volume<5DHV
Median opening should
not be permitted except to
accommodate,large traffic-
generating facilities such
as large shopping centers
or industrial plants.Median
openings may be
permitted in these
instances if satisfactorily
justified to account for
turning movements.
The department reserves
the right o close an
existing median opening
when the department
deems it is necessary.
Median
crossovers,existing prior
to construction of a
driveway or local road,may
require modification to
accommodate the
projected traffic
movements. Cost incurred
for such modifications will
be borne by the owner.
If access point are off-set,
then right-in/right-out
entrances shall be
utilized.
Minimum safe sight
distance must be provided
for the vehicles turning left
from a major roadway.Two-
way left turn lanes may be
provided onto a Mobility
Arterial to accommodate
left turns, as a MaineDOT
mitigation of traffic
imapcts from a proposed
entrance.
Iowa Primary Road
Access Management
Policy December 2005
Driveway Manual
(March 2,2004)
Not available online
Not available online
Access Management
Guidance
Highway Driveway and
Entrance Rules
LT-in/out allowed with
appropriate median
opening design.
Corridor Management
Policy
In extreme cases, where
corner clearance is not
sufficient,a right-in/right-
out entrance may be
considered, provided a
non-traversable median is
constructed to prevent left
turns.
Right-turn in/out only
driveways were not
specifically addressed.
INDOT Driveway Permit
Manual 1996
Where left turns are
needed,dedicated left turn
lanes should be provided
on the driveway for
required level of service
above "C",and left turns
deceleration lanes on the
highways should also be
provided to enter the
approach safely.High
volume traffic generators
such as shopping
centers, industrial
plants,industrial parks,
residential projects,and
similar developments may
have a median crossover
desirable.
Major driveways into
developments such as
shopping centers should
be constructed to prevent
cross traffic movement of
internal traffic within 100ft
from the highway edge of
pavement.This may be
accomplished by the use
of a raised island.
Raised islands are used to
channelize the movements
at a driveway where only
right turns are allowed.
Commercial/Industrial Entrance onto
Curbed/Uncurbed Highways
Driveway channelization
has been used on the
sketches given by Ksdot
Manual,but did not
address clearly on right
turn in/out only driveways.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Median openings
allowing full access
cannot be evaluated
independent of
direction. Median
openings are allowed
only when spacing
requirements can be
met for both sided of
the roadway.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Not available onlineIllinois
Residential Entrance onto Curbed Highways
Idaho
Kansas
Indiana
Iowa
Kentucky
Maine
Georgia
Hawaii
Lousiana
One Way Access
Two Way Access
16
35
42
22
Not available online
Note:These measurements shall be taken from intersection of property lines at the
corner to the edge of driveway.
Note: Driveways which are channelized with a median island separating the egress
and ingress vehicular movements will use the appropriate one-way dimensions on
this chart.
Att signalized intersections,the minimum corner clearance should be
equal to the average signal queue length.
At unsignalized intersections,corner clearance distances need only be
sufficient to ensure adequate and unrestricted turning movements by
driveway traffic.
Appendix 1. Summary of Turn Restriction Policies
Documentation Full Access Width Criteria
RT-in/out LT-in/out Vehicular Volume/Type of Driveway Min (ft) Max (ft) Access Class
Median Type or
Speed (mph) or
Control
Min Distance(ft)
Width of Driveway
Driveway Width Corner Clearance at IntersectionDriveway Spacing
(Distance of Driveway from the Intersection)
State
Rules for Driveway movements
Restrictive Access
Criteria
Min Driveway Spacing(ft)
Spacing Criteria
NCHRP reports
AASHTO advises that
driveways not to be
permitted within the
functional area of an
intersection, therefore
there should be sufficient
corner clearance to
separate access
connections from roadway
intersections.Where no
alternatives exist, common
practice is for the
permitting department to
allow construction of an
access connection along
the property line farthest
from the intersection.In
such cases, agencies
typically reserve the right
to require directional
connections (i.e., right-
in/out, right in only, or right
out only) or to require
nonconforming corner
properties to share access
with abutting properties. (Access Management
Manual 2003)
No information was found
when left turns are
allowed,but can be
derived from the
information given in RT-
in/out column.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Commercial Twoway entrances 25 35 Highway classification Preffered distance Minimum distance
Commercial Oneway entrances 17 20 Primary 400* 200*
RightIn/RightOut Entrances if commercial vehicle present Secondary-Arterial 200 100
RightIn/RightOut Entrances if Predominantly passenger cars Secondary-Collector 150 75
Single driveway or two-family driveway 9 16 Speed on Roadway Spacing Signalized Intersection Control
Two-way driveway 30 (mph) 230 ft
25 130 Stop Sign Intersection Control
30 185 115 ft
35 245
40 300 Note: These values assume a 30 to 35 mph posted speed.
45 350 For a posted speed of 40 to 55 mph, these values
50 455 should be doubled.
55 455+
Posted Speed Limit
(mph)
(feet)(2)(4)
(feet) (1)(2)(3)
40 … 305
45 50 360
50 75 425
55 100 495
60 100 570
65 … 645
No of Access locations per mile
Rural 3** 1000
Undeveloped Urban 7** 600
UrbanProvide access to all
properties**Consider Consolidation of drives
85th Percentile Speed (mph)
Class I (Non Commercial) 12 24 25 150
ClassII( Minor Commercial) 32 48 30 200
Class III(Major Commercial) 32Max width depends on the lane
requirement and traffic impact
report. 35 250
For SU *16 *22 40 300
For WB-50 *16 *26 45 350
50 450
*May alter depending on curb radius. 55 600
60 800
65 1000
70 1200
Access Control Policy to
the State Highway
System
Access Management
Manual
MDOT Manual
(currently not available
online)
Not available online
In order to separate
conflicting turning
movements into and out of
property, "right-in only",
"right-out only" or "left-turn
only" access by
channelization islands
may be
effective.Particularly on
corner properties,allowing
"right-turn only" in and out
can cut down on left-turns
near
intersections.However,
raised medians are the
most effective practice to
reduce conflicts
associated with left turns.
Not available online
Not available online
State Highway Access
Manual
Not available online
On existing roadways, the
entrance should be limited
to right-in/right-out only,
unless weaving or other
traffic operations indicate
the need for further
restrictions on turning
movements (e.g. right-in
only or right-out only). On
the planned divided
roadways, access will be
limited to right-in/right-out
movements when the
median is constructed.
Commercial two-way
entrances are
acceptable along a
divided highway only
if there is an
approved full
movement median
opening at the site
access, whereas on
undivided highway
commercial two-way
entrances are
appropriate where no
turning movement
restrictions is
required.
Min 20' one way width
Min 17' one way width
Residential, commercial,
industrial or institutional
uses may be granted
additional access if it is
determined to benifit site
circulation and overall
corridor operations. If
multiple access points are
being considered, the
additional access points
may be limited to 3/4
movement (right-in/right-
out/left-in only), right-
in/right-out only, right-in
only,or right-out only.
Not addressed
specifically,but can
be derived from the
turning restrictions.
Not addressed
specifically, but can be
derived from the turning
restrictions.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Rural(Type1& 2) Rural &
Urban/Urbanizing(Type 3)
Commercial right-in/right-
out entrances shall be
used on all divided
highways with posted
speeds above 40 mph.
Alternatively,in urban
street environments where
posted speeds are 40
mph or lower and a narrow
raised median separates
the directional highways,
other commercial
entrances may be used as
long as appropriate
signing is provided to
discourage errant
movements.
A minimum 20' tangent is required between adjacent entrances on the same side of Highway under any
circumstances.
Driveway spacings are
based on speed to reduce
collision potential due to
right-turn conflict overlaps
as well as providing
reasonable egress
capacity.
Not addressed
specifically.
Access Management
System and Standards
In one-way commercial
entrances, directional
control restricting left
turns may be provided.
Not addressed
specifically.
Massachusetts
Michigan
Minnesota
Maryland
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
Not available online
*On primary highways,entrances may not be located within the influence area
of dedicated right or left turning lanes for the adjacent intersection.
A minimum 20' tangent is required between adjacent entrances on the same side of Highway under any
circumstances.
Appendix 1. Summary of Turn Restriction Policies
Documentation Full Access Width Criteria
RT-in/out LT-in/out Vehicular Volume/Type of Driveway Min (ft) Max (ft) Access Class
Median Type or
Speed (mph) or
Control
Min Distance(ft)
Width of Driveway
Driveway Width Corner Clearance at IntersectionDriveway Spacing
(Distance of Driveway from the Intersection)
State
Rules for Driveway movements
Restrictive Access
Criteria
Min Driveway Spacing(ft)
Spacing Criteria
NCHRP reports
AASHTO advises that
driveways not to be
permitted within the
functional area of an
intersection, therefore
there should be sufficient
corner clearance to
separate access
connections from roadway
intersections.Where no
alternatives exist, common
practice is for the
permitting department to
allow construction of an
access connection along
the property line farthest
from the intersection.In
such cases, agencies
typically reserve the right
to require directional
connections (i.e., right-
in/out, right in only, or right
out only) or to require
nonconforming corner
properties to share access
with abutting properties. (Access Management
Manual 2003)
No information was found
when left turns are
allowed,but can be
derived from the
information given in RT-
in/out column.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Residential 8 26 Posted speed limit Spacing Distance 12
Non -residential 20 85
25 105
30 125
Two-way operation 20 Max allowable=46 35 150 (i) All access level 6 roadways;
Fire house Max allowable=100 40 185
45 230
50 275
55 330
Non-traversable median
Full Access Partial Access
UPA(Urban Principal Arterial) ≤30mph 1320 200
35 to 40mph 1320 325
45 to 50mph 1320 450
≥55mph 1320 625
UMA(Urban Minor Arterial) ≤30mph 660 175
35 to 40mph 660 275
45 to 50mph 660 400
≥55mph 1320 600
UCOL(Urban Collector) ≤30mph 330 150
35 to 40mph 330 225
45 to 55mph 660 350
Same Minimun Spacing requirements with Traversable Median as for Partial Access
Driveway with two-way operations 20 36
Driveway with one-way operation 12 24 100
50
Extend beyond 100'
Criteria
Where the property's road frontage allows
At no time shall it be less than
Policy on Street and
Driveway Access to
North Carolina
Highways(July 2003)
If access connections
have to be located within
the functional area due to
limited property frontage,
the NCDOT may restrict
access to "right-in/right-
out" or other limited
movement
treatments.Such
driveways must still meet
all location and minimum
distance requirements.In
locations where the sight
distance cannot be met on
both sides of the driveway
location, the driveway may
be denied. In some cases,
the left turn movements
into or out of the driveway
may be prohibited.
with
non-traversable median.
Restrictions to full left-turn
access may be required
due to safety or
operational deficiencies
that would be expected if a
full access median was
implemented.Restricted
movements to right-in/out
only, should be prohibited
through geometric design
and channelization
Not addressed
specifically,but can
be derived from the
turning restrictions.
Median openings at
intersections or full-
access driveways
should be spaced
with a minimum
frequency based
upon the access
category and posted
speed of the
highway.
Medians should be
designed to accommodate
the largest design vehicle
anticipated to use the
access, and may provide
either partial or full
access.
North Carolina
North Dakota
New Mexico
New Jersey
New York
20One-way operation
Highway infrastructure
improvements may be
necessary for safe and
efficient traffic operations
when there are high
roadway and/or turning
volumes of traffic,when
the roadway speeds are
moderate or high, or
where needed due to
limited sight
distance.Highway
infrastructure
improvements include, but
are not limited to
additional through lanes,
acceleration lanes, and
turn lanes for left and right
turns associated with a
driveway.
On most state
maintained routes,
the minimum
distance between
the centerlines of full-
movement driveways
into developments
that generate high
traffic volumes
should be at least
600 ft.However ,on
routes with safety,
congestion, or
operatioanl
problems, 1000 ft or
more may be
required between the
centerline of any left
turn access points
and any adjacent
street and
driveways.
For full movement driveway connections at
signalized intersections and when the
property's road frontage allows
High Volume Generator- A land or development that has an
average daily traffic greater than 1000 vehicles per day. Corner clearance is from the point of tangency of the radius curvature
of the intersecting streets to the proposed driveway.
Min distance between the centerlines of full
movement driveways into developments that
generate high traffic volumes
600
For single-family residential driveway
State Highway Access
Management Code
(Publidhing date not
mentioned, expires on
April 11, 2012)
(1)If future traffic volumes
could warrant installing a
traffic signal and
signalized spacing
requirements cannot be
met , as a condition of the
access permit, the
commissioner may, at
such time as future
volumes are reached
,close the left turn access
in accordance with
N.J.A.C. 16:47-4.33(b).(2)
If an undivided highway
becomes divided, as a
condition of the access
permit,the Commissioner
may at such time close the
left-turn access in
accordance with N.J.A.C.
16:47-4.33(b).
Left turn access shall be
prohibited if the criteria
for left turn lane have
been met but there is
insufficient space for a
left turn lane,unless the
commissioner
determines that left-
turns can be made
safely,considering traffic
volumes and sight
distances.
On routes with safety, congestion and operational
problems1000The need for wider driveways will be considered on a case-by-
case basis only after justification of actual necessity, but should
not exceed 50 feet.
State Access
Management Manual
100
Max desireable=34
Max allowable=40
All driveways in the vicinity of unsignalized
intersections, except for single-family
residential driveways, on any one of the
following:
All driveways in the vicinity of signalized
intersections and locations not covered in
criterion 1 and 2 above
50
(ii) All roadways with a posted speed limit of 25
miles per hour; or (iii) All locations with at least
a 10 foot shoulder
Appendix 1. Summary of Turn Restriction Policies
Documentation Full Access Width Criteria
RT-in/out LT-in/out Vehicular Volume/Type of Driveway Min (ft) Max (ft) Access Class
Median Type or
Speed (mph) or
Control
Min Distance(ft)
Width of Driveway
Driveway Width Corner Clearance at IntersectionDriveway Spacing
(Distance of Driveway from the Intersection)
State
Rules for Driveway movements
Restrictive Access
Criteria
Min Driveway Spacing(ft)
Spacing Criteria
NCHRP reports
AASHTO advises that
driveways not to be
permitted within the
functional area of an
intersection, therefore
there should be sufficient
corner clearance to
separate access
connections from roadway
intersections.Where no
alternatives exist, common
practice is for the
permitting department to
allow construction of an
access connection along
the property line farthest
from the intersection.In
such cases, agencies
typically reserve the right
to require directional
connections (i.e., right-
in/out, right in only, or right
out only) or to require
nonconforming corner
properties to share access
with abutting properties. (Access Management
Manual 2003)
No information was found
when left turns are
allowed,but can be
derived from the
information given in RT-
in/out column.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Nominal Width (Commercial) Posted Speed (mph) Min Distance
Two-way 26 32 25 155ft
30 200ft
35 250ft
40 305ft
45 360ft
50 425ft
55 495ft
60 570ft
65 645ft
Speed, mph Spacing
20 120
25 190
30 320
35 450
40 620
45 860
50 1125
55 1500
a. For driveways without curb: Principal arterial 600 Principal arterial 600
i) A minimum use driveway 10 Minor arterial 400 Minor arterial 400
ii) Low and medium volume driveways Major collector 200 Major collector 200
for one-way operation 10
for two-way operation 20 Note: Note:
> Driveway spacing is measured from the end of one driveway radius to > Corner clearance shall meet the driveway spacing standards
the beginning of the next driveway radius. that are desirable for arterial and major collector roads
> Driveways shall be aligned with other driveways and roadways on the > If the minimum driveway spacing standards cannot be achieved
opposite side of the intersecting roadway on arterials and major collector due to constraints, the following shall apply in all cases:
b. For driveways with curb: i) There shall be a minimum 10-foot tangent distance between the
i) A minimum use driveway 12 end of the intersecting roadway radius and the beginning radius
ii) Low and medium volume driveways
for one-way operation 12 ii) The distance from the nearest edge of cartway of an
for two-way operation 22 intersecting roadway to the beginning radius of a permitted
Residential 10 20 Rural 40
Commercial(for oneway use) 20 Urban 20
Commercial(for twoway use) 35
Widths are both for rural and urban driveways.
Urban Commercial (One-way) 14 24 Operating Speed min c/c spacing Typical cornerlot commercial driveways 75
Urban Commercial (Two-way) 24 40 30 or less 100
Rural Commercial (One-way) 18 24 35 150
Rural Commercial (Two-way) 24 50 40 200
45 250
50 300
55 and above 350
iii) The design of high volume driveways shall be
based on analyses to determine the number of
required lanes.
of a permitted driveway.
driveway shall be a minimum of 30 feet.
Acess and Roadside
Management Standards
1996
Access Management
Model Ordinances for
Pennsylvania
Municipalities handbook
Driveway channelization
is used where it is found
to be necessary to
restrict particular turning
movements at a
driveway.
Ohio State's Highway
Access Management
Manual (December
2001)
Left turn movements shall
not be permitted if a
median is already
established and the
opening of the median
would not
provide, in the
determination of the
Department, any
significant operational or
safety benefits to the
general public or would be
counter to the purpose of
the median construction
and the continued function
of the highway at the
category assigned to it.
A left turn movement may
be permitted if (1) the left
turn movement does not
have the potential for
signalization, and (2) if the
Department
determines that the left
turn movement does not
cause congestion or
safety problems or lower
the level of service,
and (3) alternatives to the
left turn would cause
roadway and intersection
operation and safety
problems, and (4) does
not interfere with operation
of the street system or
access to adjacent
properties.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Access Management
Manual
Not addressedNot addressedNot addressed
Not available online
Not addressed
specifically, but can
be derived from the
turning restrictions.
The State of Rhode
Island and Providence
Plantations Rhode
Island Department of
Transportation "Rules
and Regulations
Concerning Permission
for use of state highway
rights-of-way"
Turn restrictions may
also be implemented if
the improvements that
would be required at a
driveway to achieve
acceptable levels of
service cannot be
provided due to
constraints or there is a
history of high crash
rates caused by left
turning vehicles.for high
and medium volume
driveways, channelization
islands and medians shall
be used to separate
conflicting traffic
movements into
specified lanes to
facilitate orderly
movements for vehicles
and pedestrians.
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
Appendix 1. Summary of Turn Restriction Policies
Documentation Full Access Width Criteria
RT-in/out LT-in/out Vehicular Volume/Type of Driveway Min (ft) Max (ft) Access Class
Median Type or
Speed (mph) or
Control
Min Distance(ft)
Width of Driveway
Driveway Width Corner Clearance at IntersectionDriveway Spacing
(Distance of Driveway from the Intersection)
State
Rules for Driveway movements
Restrictive Access
Criteria
Min Driveway Spacing(ft)
Spacing Criteria
NCHRP reports
AASHTO advises that
driveways not to be
permitted within the
functional area of an
intersection, therefore
there should be sufficient
corner clearance to
separate access
connections from roadway
intersections.Where no
alternatives exist, common
practice is for the
permitting department to
allow construction of an
access connection along
the property line farthest
from the intersection.In
such cases, agencies
typically reserve the right
to require directional
connections (i.e., right-
in/out, right in only, or right
out only) or to require
nonconforming corner
properties to share access
with abutting properties. (Access Management
Manual 2003)
No information was found
when left turns are
allowed,but can be
derived from the
information given in RT-
in/out column.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Urban Developed 100 speed (mph) (ft)
30 200
35 225
40 250
45 280
50 350
55 425
Design Speed (mph) Driveway Spacing (ft) Posted Speed (mph) Distance (ft)
25 155 <=30 200
30 200 35 250
35 250 40 305
40 305 45 360
45 360 >=50 425
50 425
55 495
60 570
65 645
70 730
Residential 10 27 Minor Collector 80 Collector 75
(Single-Family Duplex Shared Driveways) Major Collector 85-150 Arterial 150
Residential 18 30 Minor Arterial 185
(Multi-Unit, 5 or more Parking Spaces) Major Arteial 230-275
Commercial Regional Urban 200
(Requiring 5 or more Parking Spaces)
(Requiring 4 or fewer Parking Spaces)
One-way 18 24
Two-way * 24 30 Positiion Access Allowed Min(ft)
Two-way ** 30 40 20 115 Approaching intersection Right In/Out 115
25 155 Approaching intersection Right In Only 75
* when the single unit vehicle volume does not exceed 30 200 Departing intersection Right In/Out 230
35 250 Departing intersection Right Out Only 100
** when any one or more of the following apply to the access: 40 305
45 360
a. Multi-unit vehicles are intended to use the access. 50 425 Position Access Allowed Min(ft)
b. Single unit vehicles in excess of 30 feet in length will use the 55 495 Approaching intersection Full Access 230
Approaching intersection Right In Only 100
c. Single unit vehicles volume exceeds 5 in the peak hour. Departing intersection Full Access 230
Departing intersection Right Out Only 100
Commercial entrances (one-way drive) 16 20 250
Commercial entrances (two-way drive) 30 40
Unsignalized Partial Access
Intersections & Two Way
Full Access Entrance (4)
Entrances (3)
Urban Principal Arterial (5) 30 1050 27035 to 45 1320 325 50 1320 510
Urban Minor Arterial 30 660 270
35 to 45 660 325
50 1050 510
Urban Collector 30 660 200
35 to 45 660 250 50 1050 425
Rural Principal Arterial (6) 30 1320 27035 to 45 1320 440
50 1760 585
Rural Minor Arterial 30 1050 270
35 to 45 1050 440
50 1320 585
Rural Collector 30 660 270
35 to 45 660 360
With Restrictive Median
Not addressed
specifically, but can
be assessed from
the turning
restrictions.access.
five in peak hour.
Without Restrictive Median
Posted Speed or
Design Speed (mph)Unsignalized Access Spacing (ft)
No rules for full
access given
specifically, but is
addressed under the
column of driveway
spacings.
Highway Functional
Classification
Legal Speed Limit
(mph) (1)
Centerline to Centerline Spacing
in Feet
VirginiaRoad Design Manual
2007
On small corner parcels
left turn accessibility may
be a problem and access
to parcels may be limited
to right-in/right-out or
similarly restricted
movements.Right turn
in/outs should accompany
reasonable taper, and
channelized flow if
required
In general,when left-turn
volumes are higher than
100 vph, an exclusive left-
turn should be
considered.Dual left-turn
lanes should be
considered when left turn
hourly volumes exceed
300 VPH.Warrants for left-
turn laneson two lane
highways provided (See
details in description)
Left Turns are allowed
with appropriate median
cross over spacing and
auxilliary lanes on
highway.
Not Addressed
specifically, but can
be assessed from
the turning
restrictions.
Access Management
Manual,
Revised June 2004
Where adequate access
connection spacing
cannot be achieved, the
permitting authority may
allow for a lesser spacing
when shared access is
established with an
abutting property.Where
no other alternatives exist,
construction of an access
connection may be
allowed along the property
line farthest from the
intersection. To provide
reasonable acces under
these conditions but also
provide the safest
operation, consideration
should be given to
designing the driveway
connection to allow only
the right-in turning
movement or only the right-
in/right out turning
movements if feasible.
Roadway Design
Manual of Instruction
May 2007
Roadway approaches and
driveways that are located
too close to an intersection
can affect signal
operation.In these cases it
can be considered to
restrict access to "right-
in/out" operation only.
Restrictive medians limit
left-turns, physically or
legally, to defined locations.
Nonrestrictive medians
allow left-turns at any point
along the route.Consider
restrictive medians on
multilane limited access
highways and multilane
managed access highways
when the DHV is over
2,000.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Texas
Utah
Vermont
Tennessee
South Dakota
Not available online
Road Design Manual
(Publishing date not
mentioned)
A channelizing island is used
in a driveway throat: (1)
where left turns are
undesirable and there is a
need to restrict driveway
movements to right-in/right-
out on undivided roadways,
(2) where there is a high
accident rate or frequency
related to left-turn
movements.
Use median openings to
provide separate Left-Turn
entrances and exits at
major traffic generators. Do
median modifications to
eliminate Left-Turn out
movements (used where
there are safety or
operational problems due
to Left-Turn egress)
Not Addressed
specifically, but can
be assessed from the
turning restrictions.
Vermont Agency of
Transporatation Access
Management Program
Guidelines
Not Addressed
specifically,but can be
assessed from the turning
restrictions.
One or both left turn
movements at the access
may be permitted if the
applicant establishes to
the Agency's satisfaction
that left turn movements
would not create
unreasonable congestion
or safety problems or
lower the level of service
below Agency Policy.
Appendix 1. Summary of Turn Restriction Policies
Documentation Full Access Width Criteria
RT-in/out LT-in/out Vehicular Volume/Type of Driveway Min (ft) Max (ft) Access Class
Median Type or
Speed (mph) or
Control
Min Distance(ft)
Width of Driveway
Driveway Width Corner Clearance at IntersectionDriveway Spacing
(Distance of Driveway from the Intersection)
State
Rules for Driveway movements
Restrictive Access
Criteria
Min Driveway Spacing(ft)
Spacing Criteria
NCHRP reports
AASHTO advises that
driveways not to be
permitted within the
functional area of an
intersection, therefore
there should be sufficient
corner clearance to
separate access
connections from roadway
intersections.Where no
alternatives exist, common
practice is for the
permitting department to
allow construction of an
access connection along
the property line farthest
from the intersection.In
such cases, agencies
typically reserve the right
to require directional
connections (i.e., right-
in/out, right in only, or right
out only) or to require
nonconforming corner
properties to share access
with abutting properties. (Access Management
Manual 2003)
No information was found
when left turns are
allowed,but can be
derived from the
information given in RT-
in/out column.
Not addressed
specifically, but can
be derived from the
turning restrictions.
50 1320 495
Note: See description for details for values in parenthesis
No rules for full
access given
specifically, but is
addressed under the
column of driveway
spacings.
VirginiaRoad Design Manual
2007
On small corner parcels
left turn accessibility may
be a problem and access
to parcels may be limited
to right-in/right-out or
similarly restricted
movements.Right turn
in/outs should accompany
reasonable taper, and
channelized flow if
required
In general,when left-turn
volumes are higher than
100 vph, an exclusive left-
turn should be
considered.Dual left-turn
lanes should be
considered when left turn
hourly volumes exceed
300 VPH.Warrants for left-
turn laneson two lane
highways provided (See
details in description)
Appendix 1. Summary of Turn Restriction Policies
Documentation Full Access Width Criteria
RT-in/out LT-in/out Vehicular Volume/Type of Driveway Min (ft) Max (ft) Access Class
Median Type or
Speed (mph) or
Control
Min Distance(ft)
Width of Driveway
Driveway Width Corner Clearance at IntersectionDriveway Spacing
(Distance of Driveway from the Intersection)
State
Rules for Driveway movements
Restrictive Access
Criteria
Min Driveway Spacing(ft)
Spacing Criteria
NCHRP reports
AASHTO advises that
driveways not to be
permitted within the
functional area of an
intersection, therefore
there should be sufficient
corner clearance to
separate access
connections from roadway
intersections.Where no
alternatives exist, common
practice is for the
permitting department to
allow construction of an
access connection along
the property line farthest
from the intersection.In
such cases, agencies
typically reserve the right
to require directional
connections (i.e., right-
in/out, right in only, or right
out only) or to require
nonconforming corner
properties to share access
with abutting properties. (Access Management
Manual 2003)
No information was found
when left turns are
allowed,but can be
derived from the
information given in RT-
in/out column.
Not addressed
specifically, but can
be derived from the
turning restrictions.
Class Access Point Spacing (ft) **
Class 1 1320 Position Access Allowed Min (ft)
Mobility is the primary function Approaching Intersection Right In/Right Out 115
Class 2 660 Approaching Intersection Right In Only 75
Mobility is favored over access Departing Intersection Right In/Right Out 230*
Class 3 330 Departing Intersection Right In Only 100
Balance between mobility and access in
areas with less than maximum buildout
Class 4 250 Position Access Allowed Min (ft)
Balance between mobility and access Approaching Intersection Full Access** 230*
in areas with less than maximum buildout Approaching Intersection Right In Only 100
Class 5 125 Departing Intersection Full Access 230*
Access needs may have priority over Departing Intersection Right Out Only 100
mobility
* 125 ft may be used for Class 5 facilities with a posted speed of
** Minimum, on the same side of the highway. 35 mph or less.
** Full Access = All four movements (Right in/out; Left in/out)
Driveway Type (Commercial) Speed Limit (mph) Spacing (ft) 30 to 50 ft
One Way 15 25 25 105
Two Way 25 50 30 125
(Note: Desirable for Two Way = 30 ft) 35 150
40 185
45 230
50 275
55 330
Two Way Approach 24 40From centre of
intersection330ft(min)
Not addressed
specifically, but can
be assessed from the
turning restrictions
With Restrictive Median
Without Restrictive Median
Not addressed
specifically, but can
be assessed from
the turning
restrictions
Not addressed
specifically, but can
be assessed from
the turning
restrictions
Wisconsin Not available online
WyomingWYDOT Access
Manual
On multilane urban
arterials: If ADT > 30,000
vpd, a median island
should be installed. Direct
accesses would be right-
in/right-out only. Right turn
deceleration lanes should
be installed at the direct
accesses.
A median island would
prohibit left turn direct
access
WashingtonDesign Manual November
2007
All private access
connections are for right
turns only on multilane
facilities, unless there are
special conditions and the
exception can
be justified
Proper channelization
should be used to allow Left
Turn in/out provided there
are special conditions and
they are justified to the
satisfaction of the
department by a traffic
analysis
West Virginia
Manual on
Rules and Regulations
for
Constructing Driveways
on State Highway
Rights-of-Way
Center channelizing island
is used in a two-way
driveway to restrict entries
to
right turns in and right
turns out
Left turn in/out are allowed
after providing certain
design conditions,
mentioned in description
Appendix 2. Description of Sites
Appendix 2. Description of Sites
LT Thru RT LT Thru RT
1Walgreens driveway, W. Saginaw
Highway and Creyts Road, LansingCorner RT in/out only
(with
channelization)
Full Access
(with pavement
markings)
243 93 45 N/A 1 2 1 1 1 1
2MSU FCU driveway, W. Saginaw
Highway, Lansing
Mid-
block RT in/out only
(with
channelization)
N/AN/A due to
midblock402 55 N/A
1
(TWLT)2 N/A N/A N/A N/A
3Rite Aid driveway, SE corner of M-36
and Dexter Road. BrightonCorner RT in/out only
(with
channelization)
Full Access
(with pavement
markings)
186 96 35 N/A 1 1
4Walgreens driveway, M-21 and Linden
Road, FlintCorner RT in/out only
(with
channelization)
Full Access
(with no pavement
markings)
252 43 45 N/A 1
(TWLT)2 1 1
5 Krispy Kreme driveway, M-21, Flint Corner RT in/out only
(with
channelization)
Full Access
(with pavement
markings)
216 336 45 N/A 1 N/A N/A N/A
6 Tim Hortons driveway, M-57, ClioMid-
block RT in/out and LT-
in (with
channelization)
N/AN/A due to
midblock92 50 N/A
1
(TWLT)2 N/A N/A N/A N/A
7BP gas station and fast food restaurants,
M-21, LennonCorner RT in/out only
(with
channelization)
Full Access
(with no pavement
markings)
291 61 55 N/A 1 1 2 1
8
National City Bank and Advance Auto,
NE Quadrant of US-12 (Chicago Road)
and Michigan Avenue, Coldwater
Corner
RT-in only (with
channelization)
Full Access
(with no pavement
markings)
242 42 35 N/A 1 1
9
Family Video driveway, SE corner of M-
66 (Capital Ave) and Emmett Street,
Battle Creek
Corner
RT-in only (with
channelization)
Full Access
(with no pavement
markings)
201 54 25 N/A 1 1
Number of LanesDistances (ft)
1 2 Corner Clearance
Distance from
Adjacent
Driveway
Posted Speed (mph)Driveway Configuration
Road Adjacent
to Driveway 1
1
2 1
Road Adjacent
to Driveway 2
Road Adjacent to
Driveway 1
Road Adjacent to
Driveway 2
1 2
Site # Study Site TypeSchematic Site
Layout
1 1
2
2
Appendix 3. Manual Data Collection Forms
FIELD DATA WORKSHEET FOR TRAFFIC VOLUMES
General Information
Site/Location ________________________________________________________________________________________________________
Date (mm/dd/yy) ___________________________ ________________________________________
Name of Person Collecting Data ______________________ Analysis Time Period ________________________________________
Type of Driveway Control
Driveway Geometry
Traffic Volumes
Thru(2) Thru(1) RT-in(1) RT-out(1) Thru(5) Thru(4) LT-in(4) LT-out(4) LT-Lane(3) Lane(2) Lane(1)
1
2
3
4
5
6
7
8
General Observations/Notes:__________________________________________________________________________________________________________________________________
__________________________________________________________________________________________________________________________________
__________________________________________________________________________________________________________________________________
__________________________________________________________________________________________________________________________________
__________________________________________________________________________________________________________________________________
__________________________________________________________________________________________________________________________________
__________________________________________________________________________________________________________________________________
______________________________________________________________________________
Time
Period Direction:________________
No of Vehicles in Queue during counting
intervalsTime Interval
(15min)
Near Far
Volume
Direction:________________
RT In/Out + LT In RT In/Out + LT Out
Non-Restricted
Restricted : RT In/Out Only
TRAVEL TIME DATA COLLECTION FORM
NAME OF THE OBSERVER: _______________________________________ NAME OF THE STREET: ________________________________________________
DATE: ____________________________ TIME: _____________________ WEATHER: ___________________________________________________________
START TIME END TIME START TIME END TIME START TIME END TIME
1
2
3
4
5
6
7
8
9
10
* Time between starting and ending point
INTERMEDIATE STOPSRUN
NUMBER*END TIME*START TIMEDIRECTION
Appendix 4. Crash Data Summary for All Sites
Before After
Site 1 33,200 Right-in/Right-out 209 3 in 4 years None in 4 yearsreduction in driveway-related crashes after
restricting the driveway to right turns only
Control Site 1 19,857 Full access 170
driveway-related crashes have been observed
almost every year 2000-2007 involving left
turning movements
Site 4 18,400 Right-in/Right-out 224 5 in 3 years 1 in 5 yearsreduction in driveway-related crashes after
restricting the driveway to right turns only
Control Site 4 20,800 Full access 150
driveway-related crashes have been observed
from 2000-2007 involving left turning
movements
Site 5 27,200 Right-in/Right-out 182 none in 4 years 1 in 4 years only crash was due to left turning violation;
effect of turning restriction not clear
Control Site 5 27,200 Full access 185all 3 driveway-related crashes involved left
turning movements
Site 9 14,800 Right-in only 224 3in 5 years none in 2 yearsreduction in driveway-related crashes after
restricting the driveway to right turns only
Control Site 9 15,083 Full access 150
driveway-related crashes have been observed at
this site from 2000-2007 involving left turning
movements
Site 8 17,170 Right-in only 252
due to proximity of next development, no clear
information was found regarding whether the
driveway-related crashes were related to this
driveway or the one next to it
Control Site 8
9648
(medium
volume)
Full access 275
in spite of not having high traffic volume, left-
turning movements were found to be involved in
all the driveway-related crashes
Corner Sites
5 in 8 years, before and after periods not clear
(probably no change)
3 in 8 years (site was not changed since at least
2001)
Appendix 4. Crash Data Summary for All Sites
Corner Clearance
(ft)Remarks
Volume
CategorySite number ADT (vpd) Type of control
Number of driveway-related crashes
4 in 8 years, before and after periods not clear
(probably no change)
no clear information found
3 in 8 years-before and after periods not clear
(probably no change)
High
Volume*
9 in 8 years, before and after periods not clear
(probably no change)
Before After
Corner Sites
Appendix 4. Crash Data Summary for All Sites
Corner Clearance
(ft)Remarks
Volume
CategorySite number ADT (vpd) Type of control
Number of driveway-related crashes
Site 3 11,210 Right-in/right-out 256 1 in 3 years none in 4 years
the only crash that occurred before the site was
changed involved left turning movement.low
crash frequency in general, effect of turning
restriction not clear
Control Site 3 5,390 Full access 200no crashes during entire period at this low-
volume site
Site 7 4,480 Right-in/Right-out 229 none in 4 years none in 4 years
no crashes during entire period at this low-
volume site; suggests that turning restrictions not
necessary
Control Site7 11,893 Full access 100
high number of driveway-related crashes at full-
access driveway, mostly involving left-out
movements; very low corner clearance may also
have an effect
Site 2 28,100 Right-in/Right-out N/Alow crash frequency in general, effect of turning
restriction not clear
Control Site 2 17,100 Full access N/A
driveway-related crashes have been observed at
this mid-block site from 2000-2007 involving
left turning movements
Control Site 6 38,140 Right-in/Right-out N/A the only crash that occurred at this restricted
driveway was caused by left-turning violation
* high volume = ADT>15,000vpd
none in 8 years
3 in 8 years, before and after periods not clear
(probably no change)
Site 6
Corner Sites (continued)
Mid-Block Sites
no driveway -related crash was found, effect of
turning restriction not clear
Right-in/Right-out/Left-
inN/A
High Volume
1 in 8 years, before and after periods not clear
(probably no change)
38,140
Low to
Medium
Volume
12 in 8 years (site was not changes since 2001
but could be there even before that)
none in 8 years
none in 8 years
Appendix 5. Additional Results for Model 1
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=250ft)
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Figure 5-1. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Figure 5-2. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=250ft)
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
Figure 5-3. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
Figure 5-4. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=350ft)
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Figure 5-5. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Figure 5-6. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=350ft)
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
Figure5-7. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
Figure 5-8. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
D
C
D
C
Appendix 6. Results for Model 2
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=150ft)
Figure 6-1. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 6-2. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=150ft)
Figure 6-3. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 6-4. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=250ft)
Figure 6-5. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 6-6. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=250ft)
Figure 6-7. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 6-8. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=350ft)
Figure 6-9. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 6-10. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=350ft)
Figure 6-11. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 6-12. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
50th Percentile Queue Length (ft)
Figure 6-13. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=10vph
Figure 6-14. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=50vph
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=250ft
CC=350ft
CC=150ft
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=150ft
CC=250ft
CC=350ft
Appendix 7. Results for Model 3
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=150ft)
Figure 7-1. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 7-2. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=150ft)
Figure 7-3. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 7-4. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=250ft)
Figure 7-5. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 7-6. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=250ft)
Figure 7-7. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 7-8. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=350ft)
Figure 7-9. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 7-10. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=350ft)
Figure 7-11. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 7-12. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
50th Percentile Queue Length (ft)
Figure 7-13. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=10vph
Figure 7-14. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=50vph
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=250ft
CC=350ft
CC=150ft
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=150ft
CC=250ft
CC=350ft
Appendix 8. Results for Model 4
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=150ft)
Figure 8-1. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 8-2. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=150ft)
Figure 8-3. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 8-4. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=250ft)
Figure 8-5. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 8-6. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=250ft)
Figure 8-7. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 8-8. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=350ft)
Figure 8-9. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 8-10. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=350ft)
Figure 8-11. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 8-12. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
50th Percentile Queue Length (ft)
Figure 8-13. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=10vph
Figure 8-14. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=50vph
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=250ft
CC=350ft
CC=150ft
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=150ft
CC=250ft
CC=350ft
Appendix 9. Results for Model 5
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=150ft)
Figure 9-1. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 9-2. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=150ft)
Figure 9-3. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 9-4. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=250ft)
Figure 9-5. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 9-6. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=250ft)
Figure 9-7. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 9-8. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=350ft)
Figure 9-9. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 9-10. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=350ft)
Figure 9-11. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 9-12. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
50th Percentile Queue Length (ft)
Figure 9-13. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=10vph
Figure 9-14. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=50vph
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=250ft
CC=350ft
CC=150ft
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=150ft
CC=250ft
CC=350ft
Appendix 10. Results for Model 6
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=150ft)
Figure 10-1. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 10-2. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=150ft)
Figure 10-3. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=10vph
Figure 10-4. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=150ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=250ft)
Figure 10-5. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 10-6. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=250ft)
Figure 10-7. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=10vph
Figure 10-8. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=250ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=350ft)
Figure 10-9. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 10-10. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=350ft)
Figure 10-11. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=10vph
Figure 10-12. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for CC=350ft, and LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
50th Percentile Queue Length (ft)
Figure 10-13. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=10vph
Figure 10-14. Comparison of 50% Queue Length (ft) for Through Traffic vs. Mainline Volume (vph) for CC=150ft, 250ft and 350ft, LT=50vph
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=250ft
CC=350ft
CC=150ft
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
250 500 1000 1500 2000
Mainline Volume (veh/hr)
50
% Q
ue
ue
Le
ng
th f
or
Th
rou
gh
Ma
inlin
e T
raff
ic (
ft)
No Driveway
RT-in only (DV=25vph)
RT-in only (DV=150vph)
RT-in/out only (DV=25vph)
RT-in/out only (DV=150vph)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
CC=150ft
CC=250ft
CC=350ft
Appendix 11. Results for Model 7
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=150ft)
Figure 11-1. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for LT-in Vol=10vph
Figure 11-2. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=150ft)
Figure 11-3. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for LT-in Vol=10vph
Figure 11-4. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=15vph0)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C
Appendix 12. Results for Model 8
Average delay (sec/veh) for LT-in traffic for different turning volumes (CC=150ft)
Figure 12-1. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for LT-in Vol=10vph
Figure 12-2. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-i
n D
ela
y a
t th
e D
riv
ew
ay
(s
ec
/ve
h)
RT-in/out+LT-in only (DV=25vph)
RT-in/out+LT-in only (DV=150vph)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS C
LOS D
Average Delay (sec/veh) for LT-out traffic for different turning volumes (CC=150ft)
Figure 12-3. Comparison of Average LT-out Delay (sec/veh) vs. Mainline Volume (vph) for LT-in Vol=10vph
Figure 12-4. Comparison of Average LT-in Delay (sec/veh) vs. Mainline Volume (vph) for LT-in Vol=50vph
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
0
20
40
60
80
100
120
140
160
180
200
250 500 1000 1500 2000
Mainline Volume (veh/hr)
Av
g. L
T-o
ut
De
lay
at
the
Dri
ve
wa
y (
se
c/v
eh
)
Full Access (DV=25vph)
Full Access (DV=150vph)
LOS
LOS
D
C
D
C